Comparison of Speech Intelligibility Measurements with ...etd.dtu.dk/thesis/242416/SebastianAlexDalgas_Comparison_of_Speec… · Comparison of Speech Intelligibility Measurements

Master thesis

Comparison of SpeechIntelligibility Measurements

with ODEON ModelSimulations

Sebastian Alex Dalgas Oakley, s011913

Supervisor:Torben Poulsen, Ørsted, DTU

March 14, 2008

Technical University of Denmark

Ørsted · DTU

Abstract

ODEON modeling software is widely used by acoustic engineers todesign rooms so they contain a set of desired acoustical characteris-tics, such as the reverberence of a concert hall or the privacy of anoffice complex. ODEON is also used by research groups to simulateenvironments, which can be used for, amongst other things, speechintelligibility experiments. However, the validity of such speech intel-ligibility experiments is called into question as no direct comparisonbetween real room speech intelligibility results and simulated roomspeech intelligibility results has been made.

This project compares speech intelligibility measurements made inreal room situations with speech intelligibility measurements made inequivalent ODEON-simulated rooms. Comparisons of speech transmis-sion index values in the real rooms and the ODEON-simulated roomsare carried out. Speech intelligibility results from 15 test subjects havebeen measured and are presented.

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Abstract

ODEON bliver brugt af akustiske ingeniører til at designe rum så debestår af visse ønskede akustiske karakteristika, så som efterklangstideni en koncert sal eller stilheden i et kontorområde. ODEON bliver ogsåbrugt af forskningsgrupper til at simulere omgivelser, som kan brugestil, blandt andet, taleforståelighedsmålinger. Dog er gyldigheden afdisse taleforståelighedsmålinger draget i tvivl da der ikke er udført no-gen direkte sammenligning mellem taleforståelighedsmålinger udført irigtige rum og taleforståelighedsmålinger lavet i simulerede rum.

Dette projekt sammenligner taleforståelighedsmålinger lavet i rigtigerum med taleforståelighedsmålinger lavet i ODEON ækvivalente simule-rede rum. Sammenligninger af speech transmission index værdier forrigtige rum og ODEON-simulerede rum er også udført. Taleforståe-lighedsresultater fra 15 forsøgspersoner er blevet målt og er præsen-teret.

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Preface

This report it the result of my masters project, which was created during thefinal stage of my education as a M.Sc. electrical engineer from the TechnicalUniversity of Denmark. My master thesis started on September 15 2007 andended March 14 2008 and culminated with this report. The projects dura-tion is equivalent to 30 ECTS points.

There were several people who helped me during this project that I wouldlike to thank:

• Hallur Johannessen for his useful assistance with the STI measure-ments.

• Iris Arweiler for helping me with any speech intelligibility questions Imay have had.

• Carl Ludvigsen from Widex for providing the additional Dantale 1word material lists.

• Jens Holger Rindel and Claus Lynge from ODEON for their help withthe ODEON models as well as the discussions regarding the results.

A special thanks goes to my supervisor Torben Poulsen for the many gooddiscussions and the helpful insight, which he has provided during the courseof the project. I would also like to thank my parents and my girlfriend fortheir love and support during this project.

Lyngby, March 2008

Sebastian Alex Dalgas Oakley

LIST OF FIGURES iv

List of Figures

1 Speech Intelligibility Psychometric Curve . . . . . . . . . . . 42 Intelligibility test procedure overview . . . . . . . . . . . . . . 53 Dantale 1 reference data . . . . . . . . . . . . . . . . . . . . . 74 Dantale 1 Speech and Noise Spectrum . . . . . . . . . . . . . 75 Dantale 1 list intelligibility . . . . . . . . . . . . . . . . . . . . 86 Dantale 2 Reference Data . . . . . . . . . . . . . . . . . . . . 107 Dantale 2 Noise . . . . . . . . . . . . . . . . . . . . . . . . . . 108 Dantale 2 Speech and Noise Spectrum . . . . . . . . . . . . . 119 STI overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 1310 STI/Intelligibility Relationship . . . . . . . . . . . . . . . . . 1311 Room 019/352 . . . . . . . . . . . . . . . . . . . . . . . . . . 2612 Auditorium 021/341 . . . . . . . . . . . . . . . . . . . . . . . 2613 Real room Dantale 2 Track Waveform . . . . . . . . . . . . . 2814 Simulated room Dantale 2 Track Waveform . . . . . . . . . . 2915 Real room measurement setup . . . . . . . . . . . . . . . . . . 3316 Measurement Procedure for Simulated Room Measurements . 3417 Measurement Procedure for Real Room Measurements . . . . 3418 STI Measurement Setup . . . . . . . . . . . . . . . . . . . . . 3519 Speech intelligibility for Classroom 019/352, Dantale 1, posi-

tion 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3920 Speech intelligibility for Classroom 019/352, Dantale 2, posi-

tion 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4021 Speech Intelligibility for Classroom 019/352, Dantale 1, Posi-

tion 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4122 Speech Intelligibility for Classroom 019/352, Dantale 2, Posi-

tion 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4223 Speech Intelligibility for Auditorium 021, Dantale 1, Position 1 4324 Speech Intelligibility for Auditorium 021, Dantale 2, Position 1 4425 Speech Intelligibility for Auditorium 021, Dantale 1, Position 2 4526 Speech Intelligibility for Auditorium 021, Dantale 2, Position 2 4627 Mean Speech Intelligibility Curves for Classroom 019/352 . . 5128 Mean Speech Intelligibility Curves for Auditorium 021/341 . . 5129 Real room measurement setup . . . . . . . . . . . . . . . . . . 8030 Pilot test 1, Dantale 1 speech intelligibility results for audito-

rium 021/341. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8431 Pilot test 1, Dantale 2 speech intelligibility results for audito-

rium 021/341. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8532 Pilot test 1, Dantale 1 speech intelligibility results for class-

room 019/352. . . . . . . . . . . . . . . . . . . . . . . . . . . 8733 Pilot test 1, Dantale 2 speech intelligibility results for class-

room 019/352. . . . . . . . . . . . . . . . . . . . . . . . . . . 88

LIST OF FIGURES v

34 Pilot test 1, Dantale 2 speech intelligibility retest results forauditorium 021/341. . . . . . . . . . . . . . . . . . . . . . . . 89

35 Pilot test 2, Dantale 1 speech intelligibility results for audito-rium 021/341. . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

36 Pilot test 2, Dantale 2 speech intelligibility results for audito-rium 021/341. . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

37 Pilot test 2, Dantale 1 speech intelligibility results for class-room 019/352. . . . . . . . . . . . . . . . . . . . . . . . . . . 92

38 Pilot test 2, Dantale 2 speech intelligibility results for class-room 019/352. . . . . . . . . . . . . . . . . . . . . . . . . . . 93

39 Classeoom 019/352 ODEON STI Mapping - Speech Source . 9940 Classeoom 019/352 ODEON STI Mapping - Noise Source . . 9941 Auditorium 021/341 ODEON STI Mapping - Speech Source . 10042 Auditorium 021/341 ODEON STI Mapping - Noise Source . . 10043 Test Subject Recruitment Flyer . . . . . . . . . . . . . . . . . 11144 Questionnaire . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

LIST OF TABLES vi

List of Tables

1 Dantale 2 Words . . . . . . . . . . . . . . . . . . . . . . . . . 92 Classroom 019/352 and Auditorium 021/341 Dimensions . . . 273 Speech and Noise Source Coordinates . . . . . . . . . . . . . . 274 Position 1 and 2 Coordinates . . . . . . . . . . . . . . . . . . 275 Measurement Program . . . . . . . . . . . . . . . . . . . . . . 316 Psychometric curve data for Classroom 019/352, Dantale 1,

Position 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397 Psychometric curve data for Calssroom 019/352, Dantale 2,

Position 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408 Psychometric Curve Data for Classroom 019/352, Dantale 1,

Position 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 419 Psychometric Curve Data for Classroom 019/352, Dantale 2,

Position 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4210 Psychometric Curve Data for Auditorium 021/341, Dantale

1, Position 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4311 Psychometric Curve Data for Auditorium 021/341, Dantale

2, Position 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4412 Psychometric Curve Data for Auditorium 021/341, Dantale

1, Position 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4513 Psychometric curve data for Auditorium 021/341, Dantale 2,

Position 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4614 Classroom 019/352 STI Results . . . . . . . . . . . . . . . . . 4715 Auditorium 021/341 STI Results . . . . . . . . . . . . . . . . 4816 Classroom 019/352 Additional STI Results . . . . . . . . . . . 4817 Headphone Attenuation Levels . . . . . . . . . . . . . . . . . 7918 Pilot test 1 simulated auditorium 021/341 training track results. 9519 Pilot test 1 simulated room 019/352 training track results. . . 9620 Pilot test 2 simulated auditorium 021/341 training track results. 9721 Pilot test 2 simulated room 019/352 training track results. . . 9822 Dantale 1 word lists 1-8 . . . . . . . . . . . . . . . . . . . . . 10123 Dantale 1 word lists 9-16 . . . . . . . . . . . . . . . . . . . . . 10224 Dantale 1 word lists 17-24 . . . . . . . . . . . . . . . . . . . . 10325 Dantale 1 word lists 25-32 . . . . . . . . . . . . . . . . . . . . 10426 Dantale 1 word lists 33-40 . . . . . . . . . . . . . . . . . . . . 10527 Dantale Material List Distribution . . . . . . . . . . . . . . . 11028 Loudspeaker Calibration Values . . . . . . . . . . . . . . . . . 11329 Dantale 1 score sheet example . . . . . . . . . . . . . . . . . . 11430 Dantale 2 test subject intelligibility score sheet excerpt . . . . 11531 Dantale 1 Response Sheet Example . . . . . . . . . . . . . . . 116

CONTENTS vii

Contents

List of Figures iv

List of Tables vi

Contents vii

1 Introduction 11.1 Project Origin . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Research Question . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Report Structure . . . . . . . . . . . . . . . . . . . . . . . . . 11.4 Explanation of Terminology . . . . . . . . . . . . . . . . . . . 2

2 Speech Intelligibility 42.1 Dantale 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1.1 Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.2 Dantale 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.2.1 Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3 Speech Transmission Index 123.1 Dual Input Room Acoustics Calculator - Dirac . . . . . . . . 12

4 ODEON 154.1 ODEON environment setup . . . . . . . . . . . . . . . . . . . 154.2 Speech Intelligibility Material Auralizations . . . . . . . . . . 164.3 ODEON STI . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5 Measurements Design 185.1 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . 185.2 Speech Intelligibility Measurements . . . . . . . . . . . . . . . 18

5.2.1 Variable Parameters . . . . . . . . . . . . . . . . . . . 195.2.2 Fixed Parameters . . . . . . . . . . . . . . . . . . . . . 225.2.3 Chosen Measurements and Parameters . . . . . . . . . 255.2.4 Measurement Time . . . . . . . . . . . . . . . . . . . . 275.2.5 Dantale track alterations . . . . . . . . . . . . . . . . . 285.2.6 Measurement Program . . . . . . . . . . . . . . . . . . 295.2.7 Measurement Setup . . . . . . . . . . . . . . . . . . . 325.2.8 Measurement Procedure . . . . . . . . . . . . . . . . . 33

5.3 STI Measurements . . . . . . . . . . . . . . . . . . . . . . . . 355.3.1 Measurement Setup . . . . . . . . . . . . . . . . . . . 35

5.4 Pilot Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

CONTENTS viii

6 Speech Intelligibility Results 386.1 Classroom 019/352 . . . . . . . . . . . . . . . . . . . . . . . . 38

6.1.1 Position 1 . . . . . . . . . . . . . . . . . . . . . . . . . 386.1.2 Position 2 . . . . . . . . . . . . . . . . . . . . . . . . . 40

6.2 Auditorium 021/341 . . . . . . . . . . . . . . . . . . . . . . . 426.2.1 Position 1 . . . . . . . . . . . . . . . . . . . . . . . . . 426.2.2 Position 2 . . . . . . . . . . . . . . . . . . . . . . . . . 44

7 Speech Transmissions Index Results 47

8 Discussion 508.1 Speech Intelligibility . . . . . . . . . . . . . . . . . . . . . . . 508.2 STI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528.3 ODEON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

9 Conclusion 56

10 Future Development 57

Acronym List 58

References 59

Appendices 61

A Measurement Parameter Considerations 61A.1 Speech Intelligibility Measurement Setup . . . . . . . . . . . . 61

A.1.1 Simulated Room Measurements . . . . . . . . . . . . . 61A.1.2 Real Room Measurements in Actual Rooms . . . . . . 62A.1.3 Real Room Measurements using Binaural Recordings . 62

A.2 Variable Parameters . . . . . . . . . . . . . . . . . . . . . . . 62A.2.1 Rooms . . . . . . . . . . . . . . . . . . . . . . . . . . . 63A.2.2 Source and Receiver Positions . . . . . . . . . . . . . . 63A.2.3 Speech Material . . . . . . . . . . . . . . . . . . . . . . 64A.2.4 Interfering Noise . . . . . . . . . . . . . . . . . . . . . 65A.2.5 Signal-to-Noise Ratios and Adaptive/Static Method . 65

A.3 Fixed Parameters . . . . . . . . . . . . . . . . . . . . . . . . . 67A.3.1 Speech Material Reproduction . . . . . . . . . . . . . . 67A.3.2 Binaural Hearing/HATS . . . . . . . . . . . . . . . . . 68A.3.3 Test Subjects . . . . . . . . . . . . . . . . . . . . . . . 68A.3.4 Training . . . . . . . . . . . . . . . . . . . . . . . . . . 69A.3.5 Presentation Order . . . . . . . . . . . . . . . . . . . . 69A.3.6 Setup method . . . . . . . . . . . . . . . . . . . . . . . 71A.3.7 Environmental conditions . . . . . . . . . . . . . . . . 73

A.4 ODEON Parameters . . . . . . . . . . . . . . . . . . . . . . . 73

CONTENTS ix

A.4.1 Model accuracy/details . . . . . . . . . . . . . . . . . 74A.4.2 Auralization Setup . . . . . . . . . . . . . . . . . . . . 74A.4.3 Auralization level calibration . . . . . . . . . . . . . . 75

B Project Pilot Test - Speech Intelligibility Measurements 76B.1 Test subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . 76B.2 Measurement Material . . . . . . . . . . . . . . . . . . . . . . 77B.3 Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . 78

B.3.1 Simulated Rooms . . . . . . . . . . . . . . . . . . . . . 78B.3.2 Real Rooms . . . . . . . . . . . . . . . . . . . . . . . . 79

B.4 Measurement Procedure . . . . . . . . . . . . . . . . . . . . . 81B.4.1 Simulated Room Measurement Procedure . . . . . . . 81B.4.2 Real Room Measurement Procedure . . . . . . . . . . 82

B.5 Pilot Test 1 - Auditorium 021/341 . . . . . . . . . . . . . . . 83B.5.1 Auditorium 021/341 Results . . . . . . . . . . . . . . . 84B.5.2 Discussion and Conclusions . . . . . . . . . . . . . . . 85

B.6 Pilot Test 1 - Classroom 019/352 and Retest . . . . . . . . . . 86B.6.1 Classroom 019/352 Results . . . . . . . . . . . . . . . 87B.6.2 Auditorium 021/341 Retest Results . . . . . . . . . . . 88B.6.3 Discussion and Conclusions . . . . . . . . . . . . . . . 88

B.7 Pilot Test 2 - Auditorium 021/341 and Classroom 019/352 . . 89B.7.1 Classroom 019/352 and Auditorium 021/341 Results . 90B.7.2 Discussion and Conclusion . . . . . . . . . . . . . . . . 93

C Project Pilot Test Results 95C.1 Pilot 1 - Training Results . . . . . . . . . . . . . . . . . . . . 95C.2 Pilot 2 - Training Results . . . . . . . . . . . . . . . . . . . . 97

D ODEON STI Mapping 99D.1 Classroom 019/352 . . . . . . . . . . . . . . . . . . . . . . . . 99D.2 Auditorium 021/341 . . . . . . . . . . . . . . . . . . . . . . . 100

E Dantale 1 Word Lists 101

F Dantale 2 Sentence Lists 106

G Dantale Material List Distribution Overview 110

H Flyer 111

I Questionnaire 112

J Real-Room Loudspeaker Calibration Values 113

K Test Subject Intelligibility Score Sheet 114

L Dantale 1 Response Sheet 116

M Appendix CD Contents 117

1 INTRODUCTION 1

1 Introduction

This chapter will describe the background for the project and will state theresearch question for the project. There will also be a description of thereport structure.

1.1 Project Origin

This project originated from a HearCom project, which uses ODEON-simulatedroom auralizations to measure the speech intelligibility for various acousticconditions. The validity of the intelligibility measurements was called intoquestion as no direct comparison between speech intelligibility measurementsderived from ODEON simulated rooms and real rooms have ever been made.HearCom requires the implementation of a project to investigate the validityof the speech intelligibility measurements created by ODEON.

The project concept was presented by Torben Poulsen in August 2007. Theproject officially began September 15’th 2007.

The relevance of this project transcends that of the HearCom project asODEON is a widely used room acoustic software progamme employed bothfor commercial and research purposes. Any speech intelligibility measure-ments that have been conduced based om ODEON room simulations arepotentially misrepresentative of the rooms true intelligibility. An indepth in-vestigation into the validity of speech intelligibility measurements conductedfrom ODEON simulated rooms would therefore be a widely benifitial study.

1.2 Research Question

Based on the background information mentioned the following research ques-tion has been made:

Is there any difference between the speech intelligibility measured in a realroom and the speech intelligibility measured when using an equivalent ODEONmodel auralization?

1.3 Report Structure

This report is divided into the main report and the Appendices.

The main report has ten chapters, which fully describe the project:

1 INTRODUCTION 2

• chapter 1 describes how the project originated along with the result-ing research question. An introduction to the report structure is alsodescribed.

• chapter 2 gives a description of speech intelligibility including Dantale1 and Dantale 2 material.

• chapter 3 explains the speech transmission index and how it can beused to indicate a room’s speech intelligibility.

• chapter 4 examines ODEON including how to make proper use ofODEON for speech intelligibility measurement.

• chapter 5 designs and plans all measurements used for the experimentas well as how to conduct the measurements. A short description ofmost of the parameters concerning the measurements is also discussed.

• chapter 6 presents the speech intelligibility results for both the realrooms and the simulated rooms, which are also compared.

• chapter 7 shows the STI results derived from ODEON and Dirac forboth the simulated and the real rooms respectively.

• chapter 8 discusses the speech intelligibility and STI results. The re-sults are collectively evaluated and possible explanations for the resultsare presented.

• chapter 9 draws conclusions based on the results and discussions. Theresearch question is answered.

• chapter 10 discusses how the project could be further developed.

The Appendices contain a more detailed description of the parameters con-cerning the intelligibility measurements and also describes the project pilottest that was created prior to the measurements. The Appendices also con-tains tables, figures and practical materials, which the main report refers to.There are also lists of Dantale material used for this project.

A CD containing relevant material to this project is attached to this report.Appendix M describes the CD contents.

1.4 Explanation of Terminology

There are certain terms and words used in this report that require an expla-nation.

In this report the speech intelligibility measurements derived from real roommeasurements, will be referred to as real room measurements or simply real

1 INTRODUCTION 3

measurements. Similarly, the speech intelligibility measurements derivedfrom auralizations, which are created from ODEON simulated rooms, willbe referred to as simulated room measurements or auralized measurements.

The two rooms used for the experiments, the classroom 019/352 and theauditorium 021/341 may simply be referred to as the classroom and audito-rium. The term "room" is used for both the auditorium and the classroom,as with real room and simulated room measurements.

The terms "room scenario" and "room situation" are used to classify anentire group of measurements for one room depending on whether it is areal room or a simulated room. There are therefore four different scenariosfor this project as there are two different rooms each consisting of real andsimulated measurements.

2 SPEECH INTELLIGIBILITY 4

2 Speech Intelligibility

The main goal of this project is to verify ODEON by comparing speech in-telligibility measurements from simulated rooms and real rooms.

Speech intelligibility is a subjective measurement where an amount of speechunderstood for a given situation gives a resulting speech intelligibility. Theintelligibility ranges from 0% where nothing is understood to 100% whereeverything is understood. For clinical use noise is typically introduced to thespeech to lower the intelligibility. The amount of noise presented influencesthe level of intelligibility. The intelligibility falls as the noise increases andrises when the noise increases. More specifically it is the Signal-to-Noise-Ratio (SNR) that most adequately describes the speech intelligibility as itis not the level of noise that is important but rather the ratio comparedto the speech. Since people have subjective hearing the intelligibility doesnot suddenly switch from 0% to 100% intelligibility. An SNR range can beidentified, in which the intelligibility will fluctuate and be between the 0% to100% intelligibility points. This range can be described from the cumulativenormal distibution and is called a psychometric function.

The most interesting aspect of intelligibility measurements is the intelligi-bility points between 0% and 100%; specifically the 50% point, which iscalled the speech reception threshold (SRT). A general psychometric curvefor speech intelligibility can be seen in figure 1.

Figure 1: Speech Intelligibility Psychometric Curve. The solid line represents apsychometric curve. The dashed line shows where the SRT is locatedon the curve.


The speech intelligibility can be described as a a function of SNR, if the SRTand the slope at the SRT (s50) are known:

SI(SNR) =1

1 + e−4s50(SNR−SRT )(1)

Speech intelligibility is measured by comparing speech material presented toa listener with the material reproduced by the listener. The speech materialis presented from a speaker, which reaches the listener through a transmis-sion system. The transmission system influences the speech material makingthe speech harder to understand. An overview of a speech intelligibility testprocedure can be seen in figure 2.

Figure 2: General intelligibility test procedure overview.

The manner, in which an intelligibility test is conducted and scored is de-pendent on the material used. If the material is words then the speechintelligibility score is the percentage of words understood from the wordspresented:

Speech intelligibility (%)= (100/T)×R

Where T is the number of words in the test and R is the number of correctwords.

Speech intelligibility scores are very dependent on the methods and param-eters used for the experiments. There are many factors that can influencethe outcome of speech intelligibility scores such as:

• Type of speech material. There can be large differences in intelligibil-ity difficulty depending on the speech material, whether it is words,sentences or logatomes.

• Scoring method. Defining what is the correct answer, whether it is theentire sentence, single words or logatomes.


• Speaker characteristics. The speaker influences many parameters suchas presentation speed, sound level, articulation and regional dialect.

• Listener characteristics. Factors such as fatigue, motivation, trainingand vocabulary all have an influence on the resulting speech intelligi-bility.

Several speech materials are used for measuring speech intelligibility, most ofwhich are dependent on the country one is in. In Denmark two main speechmaterials are used for clinical use: Dantale 1 and Dantale 2.

2.1 Dantale 1

Dantale 1 was created in 1986 and is a word-based speech material. A CDwas created containing a wide set of Dantale 1 material. The Dantale 1 ma-terial on the CD consists of eight word lists for adults, each list containing25 words. The 200 different words are comprised of common nouns, verbsand adjectives.[Elberling et al, 1989]

The CD also contains 3 word lists of numbers, 4 word lists for children, oneword list for very young children, and 3 tracks with fluent speech. The Dan-tale 1 words can be seen in Appendix E.

There are three ways to score the Dantale 1 material; a word score thatscores the correct number of words, a triple score that scores the correctprevocalic, intervocalic and postvocalic speech, and a phoneme score thatscores each correct phoneme.

The Dantale 1 CD also contains a noise signal, which is used to mask thespeech signals. Using the noise with the speech to create different SNRswill create a psychometric curve for the speech intelligibility. The speechintelligibility reference data for the Dantale 1 speech material using theDantale 1 noise to mask it was found by Keidser and can be seen in fig-ure 3.[Keidser, 1993]

When measuring the speech intelligibility using Dantale 1 it is common touse a few SNR values, which are hopefully within the 0% and 100% points,in order to try to estimate an SRT value.

2.1.1 Noise

The noise used for the Dantale 1 material is created from white noise, wherethe spectrum has been shaped to resemble a speech-shaped spectrum. The 3dB cutoff frequencies are at 125 and 500 Hz with a -12 dB/octave slope.


Figure 3: Dantale 1 reference data. Intelligibility points redrawn from[Keidser, 1993] and fitted as a psychometric curve.

The noise has been amplitude-modulated at 4 Hz with a -6 dB/octaveslope.[Elberling et al, 1989]The noise was intended to have the same frequency spectrum as the Dantale1 speech signal. The spectrum for both the Dantale 1 noise and speech canbe seen in figure 4.

Figure 4: Dantale 1 speech and noise spectrum. The red curve shows the longterm spectrum for the Dantale 1 speech material and the blue curveshows the long term spectrum for the Dantale 1 noise material. Figurerecreated from [Elberling et al, 1989].

The spectrum for the noise does not completely mask the speech above 1000


Hz and the slope for the noise is clearly too steep, resulting in unmaskedfrequencies above 4000 Hz. This is apparent when listening to the Dantale 1material as certain words containing high frequency components are clearlymore audible than others.

The Dantale 1 lists are not weighted with respect to these high frequencycomponents, which results in different intelligibility results for each list. Kei-dser has examined the intelligibility equivalence for all eight lists and thereis a maximum difference of 16% between lists 2 and 6. Figure 5 shows thedifferences in intelligibility for all eight lists.

Figure 5: Dantale 1 list intelligibility differences. Figure redrawn from[Keidser, 1993].

A CD containing 32 additional Dantale 1 tracks was made in 2003 by Widex.The lists are comprised of the same 200 words as the first lists. The intelli-gibility equivalence has not been examined for these lists.

2.2 Dantale 2

Dantale 2 was created in 2001 and is a sentence-based speech material. Itis based on Swedish Hagerman sentences created in 1984.[Hagerman, 1984]When the Dantale 2 material was made it was important that the intelligi-bility results generated were more homogeneous then those generated fromDantale 1.

The sentences are pseudo random sentences each with the same syntacticalstructure. The sentences are created from five 10-word lists, names, verbs,numerals, adjectives and objects, making a total of 100.000 different coher-


Dantale 2 wordsName Verb Numeral Adjective Object

Anders ejer ti gamle jakkerBirgit havde fem røde kasserIngrid ser syv pæne ringeUlla købte tre nye blomsterNiels vandt seks fine skabeKirsten får tolv flotte maskerHenning solgte otte smukke bilerPer låner fjorten store huseLinda valgte ni hvide gaverMichael finder tyve sjove planter

Table 1: Dantale 2 words, consisting of ten names, ten verbs, ten numerals, tenadjectives and ten objects.

ent sentences. The words can be seen in table 1.

160 different sentences have been created for the Dantale II CD distributedamongst 16 lists. Each sentence is comprised of the five words that havebeen recorded and segmented so as to preserve the correct co-articulationeffects. Each co-articulation combination of words has been recorded andused to combine the sentences.

There are typically two ways of scoring the Dantale 2 material. The firstis a word score that scores the correct number of words. The second is asentence score, which scores the correct number of sentences.

Dantale 2 is typically executed using an adaptive procedure so the 40% andthe 60% intelligibility points are found by regulating the SNR dependent onthe previous score. The word score is used for this procedure. The objectiveis to effectively locate the SRT.

As with the Dantale 1 material, the Dantale 2 material can also be usedusing discrete SNR values to measure the intelligibility. Material from onelist is typically used for each discrete SNR value.

The Dantale 2 material also has it own noise material. This noise is usedto mask the speech creating an SNR that is used for the speech intelligibil-ity measurements. The speech intelligibility reference data for the Dantale2 speech material using the Dantale 2 noise to mask it has been found byWagener and can be seen in figure 6.[Wagener et al, 2003]


Figure 6: Dantale 2 reference data. Figure taken from [Wagener et al, 2003].

Some of the words in each sentence have been adjusted so that the intelligi-bility for each sentence is as homogeneous as possible.

2.2.1 Noise

The Dantale noise is created by superimposing the 160 Dantale 2 sentences30 times. The sentences have random pauses inserted in between each wordin order to create a more random noise. This process can be seen in figure 7.After the sentences have been superimposed, the Dantale 2 noise no longersounds like sentences but more like modulated white noise.

Since the noise signal is created from the speech material the resulting longterm spectrum is almost identical. The spectrum for both the Dantale 2speech and noise can be seen in figure 8.

Figure 7: Dantale 2 noise created from multiple superimposed Dantale 2 sen-tences.


Figure 8: Dantale 2 speech and noise spectrum. Figure supplied by T. Poulsen

Unlike the Dantale 1 material, the long term spectrum for the Dantale 2noise fully covers the speech spectrum. The noise is actually about 2 dBhigher than the sentences.

3 SPEECH TRANSMISSION INDEX 12

3 Speech Transmission Index

The main task for this project is to compare the speech intelligibility that theODEON-simulated rooms generate with real rooms. This can be a cumber-some task and is not necessarily easy to carry out. Another way of describingthe speech intelligibility is through the use of the speech transmission index.

The speech transmission index (STI) is an objective measurement used todescribe the intelligibility from a source to a receiver. The method used forthe STI works under the assumption that the intelligibility is dependent onthe envelope of the speech signal, which must be perceived correctly. Thespeech signal is created from several modulated signals. The STI examinesthe preservation of modulation from source to receiver. This preservation ofmodulation is measured as the modulation transfer function (MTF). Addednoise and the reverberation from a room can have an influence on the mod-ulation of speech and reduce the modulation depth.

To measure the STI a noise signal with the same long-term spectrum asspeech is used. The noise is divided into seven octave bands ranging from125 Hz to 8 kHz. Each of the octave bands is then modulated 100% using 14different frequencies sequentially, ranging from 0,63 Hz to 12,5 Hz. The MTFis calculated for each of the 98 combinations. See figure 9 for an overview ofthe frequency bands used.

The MTFs are transformed to corresponding SNRs, which are truncated to±15 dB and averaged for each octave band. Each octave band SNR is thenweighted and an average SNR is found describing the MTFs. The SNR isthen normalised to produce an STI value between 0 and 1.

The STI value can be used to indicate how intelligible a point in a room is.Values range from 0 to 1 where 0 indicates a very bad intelligibility and 1an excellent intelligibility. Figure 10 shows the correlation between the STIand speech intelligibility for different types of word material.

The STI can potentially take a long time to measure and calculate. A fastermethod based on the STI called rapid STI (RASTI) was made using onlytwo octave bands, each using four and five modulation frequencies.

3.1 Dual Input Room Acoustics Calculator - Dirac

It is also possible to carry out a full STI measurement using a program calledDirac created by Brüel & Kjær. The Dirac program allows measurementssuch as STI, using an omni directional speaker at the source and a micro-


Figure 9: STI overview with 98 MTF combinations. Gray squares are for RASTImodulation frequencies. Figure from [Poulsen, 2005].

Figure 10: STI/Intelligibility Relationship for different word materials. Figurefrom [Poulsen, 2005].


phone at the receiver. Dirac calculates the STI from an impulse responsefrom the source to the receiver. This is the same method the ODEON useswhen calculating the STI.

There are several methods available when using Dirac: the Maximum LengthSequence (MLS), linear sweep or an exponential sweep.

4 ODEON 15

4 ODEON

ODEON is a room acoustic software simulation tool that can model theacoustics of a room depending on its geometry and materials.

This project uses ODEON to generate the auralized sound files that are tobe used for the speech intelligibility measurements.

4.1 ODEON environment setup

Many factors can influence the outcome of the speech intelligibility measure-ments when using auralized speech material. It is therefore a good idea thatthe correct setup is used for the ODEON model so as to create comparableresults.

For an auralized sound file it is normal to hear the sound through a set ofheadphones. This is mainly because the auralizations are binaural so theimmersiveness is fully appreciated through headphones rather then throughloudspeakers. It is possible to compensate for the headphones that are to beused for the measurements, assuming that ODEON knows the headphonesin question. This compensates for the headphones’ characteristics so theresulting auralizations are perceived as being present in the room and notthrough the headphones.

ODEON uses ray-tracing to create a point response from a source to a re-ceiver. A large amount of rays are emitted from the source to the receiverin a uniformly distributed manner. The rays travel through the room andare reflected on surfaces until they are collected at the receiver point. Thepoint response for the source to the receiver is created in this way.

The number of rays used also has an influence on the measurements. ODEONgives a recommendation for the amount of rays needed to create an adequatepoint response, which is dependent on the size of the room to be modeled.

Sources used in ODEON are by default omni-directional. For the real roommeasurements loudspeakers are used to present the material; these havea given directionality characteristic. The source can be given a directiv-ity either by a custom directivity file or by one of the existing directivityfiles that ODEON has to offer. For these measurements the directivity file"BB93_RAISED_NATURAL.SO8" is used, as it best resembles the loud-speaker configuration.

The receiver positions are binaural, which means that there is also a direc-tionality associated with it. It is possible to point the receiver positions in

4 ODEON 16

the direction of the source. This can be very beneficial for the test subjectsas this equally distributes the direct sound between each ear. This meansthat the test subject will listen equally with both ears rather than mainlylistening with a single ear.

4.2 Speech Intelligibility Material Auralizations

This project requires auralized speech intelligibility material equivalent tothe rooms used in this project. To auralize a sound file containing speechintelligibility there are a few things that need to be carried out.

The source and receiver positions must be chosen. These positions need tobe the same positions used for the real room measurements, otherwise a faircomparison cannot be made between the results. For this project there aretwo source positions: one for the speech and one for the noise.

Two point responses are created for each receiver position. One is from thespeech source position and the other is for the noise source position. Whencreating a point response an impulse response is also created.

To create the SNR for each speech material sound file, the sound file is splitinto speech and noise. The speech is convolved with the impulse responseto create the resulting speech at that receiver position. The noise signal isthen also convolved with the impulse response from the noise source positionto the receiver. After the convolutions are completed both the speech andnoise signals are mixed to create the finished binaural speech intelligibilitymaterial sound file.

The SNR can be changed for the resulting sound file simply by changingthe recording level for the convolution for either the speech signal or thenoise signal. To ensure that the speech presentation level is the same forall sound files, the speech is kept constant and the noise is regulated. It isimportant that the speech material and noise material, which is to be aural-ized initially has an SNR of 0 dB. This ensures that altering the recordinglevel for only the noise will create the wanted SNR for the auralized material.

The SNR can also be created by altering the presentation level for the noisesignal rather than the recording level. For practical reasons, altering therecording level is easiest and therefore preferred.

To ensure that all the sound files for a room are created under the sameconditions it is a good idea to create several jobs in the job list. There, anoverview of the jobs created for that ODEON-modeled room can be seen.This is also where the recording level can be altered to produce the different

4 ODEON 17

SNRs.

When recording the convolved signals it is important that they do not exceedthe 0 dB recording level, as that will result in the sound files being clipped.When all the jobs are prepared with the correct SNRs the auralized files canbe made. Running all the jobs will reveal whether any of the convolutionshave exceeded 0 dB. If so, the general recording level can be altered.

4.3 ODEON STI

ODEON can be used to calculate a number of objective measures that maybe useful in describing the acoustic properties of the room being modeled.One of these parameters is the STI, which was described in chapter 3.

As with the real STI measurements, the STI in ODEON can be calculatedfrom a source point in the room to a given receiver point, which is actualizedfrom the point response. ODEON calculates two different STI values usingtwo different methods based on the point response: one is based on theimpulse response and the other is based on the T30 reverberation time.

5 MEASUREMENTS DESIGN 18

5 Measurements Design

5.1 Requirements

For comparison purposes, four different types of measurements need to beconducted for this project:

• The speech intelligibility for a specific location measured in a real room.

• The speech intelligibility for a specific location measured in an ODEONsimulated room.

• The STI values for a specific location measured in a real room.

• The STI values for a specific location measured in a ODEON simulatedroom.

The main goal of this project is to compare the speech intelligibility measuredfrom the real rooms with those taken from the ODEON simulated rooms.Therefore, it is paramount that the measurements are in fact comparable.This means that not only must the measurement method and its parametersbe as uniform as possible but the ODEON model must be sufficiently accu-rate and detailed in order to be able to compare it to the real room.

It is important to remember that the comparison is between the ODEONmodel and the real room, so any restrictions that may be inherent in theODEON model should not be compensated for in the real measurement asthey are part of ODEON’s flaws.

5.2 Speech Intelligibility Measurements

There are many different things to consider when designing a measurementprogram. Most of the decisions made can have a direct influence on the re-sults measured and if certain parameters are chosen poorly then the resultsmay describe a different scenario or, in the worst case, be useless for theproject.

It is important to focus on the main goal of the project, which is to verifywhether speech intelligibility measurements created by ODEON auraliza-tions reflect those created from equivalent real room speech intelligibilitymeasurements. This creates two main goals for the speech intelligibilitycomparisons:

• The real room and simulated room speech intelligibility measurementsmust be comparable to each other.

• There must be a sufficient number of scenarios/measurements, withwhich to test ODEON.


It is important that the intelligibility measurements are in fact comparable,but it is also equally important that there are enough measurements, fromwhich to draw definitive conclusions. It would not be much of a validation ifonly one comparison was made, as the results would be left to pure chance.Numerous comparisons should be made so that ODEON is thoroughly tested.When determining how to test ODEON it is apparent that there are manyparameters that can be used, but that some are more relevant than others.There is also a clear distinction between which parameters are used to testODEON and which parameters are merely part of the measurements.

The types of parameters are divided into two categories:

• Variable parameters.

• Fixed parameters.

The variable parameters are the parameters with which to test ODEON. Itis these parameters, which have multiple instances that help diversify themeasurements. With several variable parameters it becomes easier to pin-point any of ODEON’s potential problem areas. By having several instancesof measurements a more representative description of the rooms are madeand less if left to chance. The variable parameters are closely tied to thegoal of having a sufficient amount of scenarios, with which to test ODEON.

The fixed parameters are the parameters, which have an influence on themeasurements, but in such a way that it would be ill advised to have severaldifferent instances of them as they may hinder any direct comparison. Thesekinds of parameters are mainly connected to the methodology used for themeasurements, to ensure uniform comparable results. The fixed parametersare closely tied to the goal of having intelligibility measurements that arecomparable to each other.

Many of the parameters are connected to each other so choosing one methodmay exclude others. See Appendix A, page 61, for a detailed descriptionof the most relevant parameters concerning this project. Appendix A alsodiscusses the contemplations that are associated with each parameter.

5.2.1 Variable Parameters

It is crucial to identify which parameters are important or could potentiallybe important to the measurements so as to create a diverse measurementprogram that adequately tests ODEON.

Most of the parameters are identified based solely on the nature of the exper-iment. Since this project has to do with speech intelligibility derived from


ODEON it is natural to examine which parameters are available when usingODEON. For example, when auralizing a sound file in ODEON, a sourceand a receiver position for a room are determined. In this case the sound filecontaining speech and noise material will be auralized and then comparedto an equivalent real room. This gives the following parameters, which itwould be beneficial to have multiple instances of:

• Rooms.

• Source and receiver positions.

• Speech intelligibility material.

• Interfering noise.

• Signal to noise ratio.

Rooms.Having different rooms in the measurement program is a good way to testODEON under completely different circumstances. There are many differenttypes of rooms that might be interesting. However, to make the measure-ments practical it should be a room on the campus area and a room that isalready modeled in ODEON.

There are several rooms on the DTU campus that have been modeled inODEON. There is a small listening room, a classroom and an auditorium.The listening room and the classroom have a similar geometry, but the class-room is bigger with harder surfaces and more details. The auditorium isdifferent in shape as the seating descends toward the blackboard and is alsomuch bigger than the other rooms. It is important that the rooms are ade-quately different, so using both the listening room and the classroom is notadvised.

It is, of course, necessary for the rooms chosen to be available in order to beable to conduct the speech intelligibility measurements in them. The roomslocated in DTU are used for classes and lectures, but they are periodicallyavailable. The rooms recommended for this project are classroom 019/352and auditorium 021/341.

Source and receiver positions.To further explore ODEON’s ability to correctly auralise sound, multiplesource and receiver positions can be used to map the intelligibility for anentire room. Mapping an entire room necessitates many receiver positionsrelative to one source position. This is very time-consuming and could po-tentially be a waste of time if all the receiver positions show the same typeof results. However, using only a few different receiver positions can give


a general impression of the sound image for both the real rooms and thesimulated rooms.

There is no real need to have several source positions, but having a few differ-ent receiver positions could be interesting. Having multiple receiver positionsensures that there is more than just one set of results with which to judgeODEON. The receiver positions should therefore be considerably differentto each other, but should still be located in similar positions for both rooms.For the classroom and auditorium there could be two receiver positions: onein the back seats and one in the front seats with a source near the blackboard.

Speech intelligibility material.In order to conduct the speech intelligibility measurements some sort ofspeech material must be used. It can be a good idea to use several types ofspeech material as they may behave differently depending on the rooms used.

Several types of speech materials can be used for this project: for exam-ple, Dantale 1 and Dantale 2. Dantale 1 has the advantage of not requiringany training but there are small fluctuations in the intelligibility generatedfrom each list, which can make it difficult to make comparisons. Dantale 2requires training before the the measurements can commence but once thetraining is completed the material should be equally intelligible for the sameSNR. Both Dantale 1 and Dantale 2 are recommended for the measurements.

Interfering noise.To generate the SNR used to measure the speech intelligibility, noise mustbe added to mask the speech signal. The type of noise used to mask thespeech can theoretically be anything. The Dantale 1 and Dantale 2 speechmaterial are supplied with their own noise. The noise is located on the rightchannel of each track on the Dantale CDs, while the speech material is onthe left channel. The noise included is calibrated in such a way, that thereis an SNR of 0 dB with respect to the speech material. By altering the noiselevel for a Dantale track the SNR is subsequently altered. It is recommendedthat the Dantale 1 and Dantale 2 noise be used for their respective Dantalespeech material.

Signal to noise ratio.Using different SNRs will generate different speech intelligibilities. Since allpeople are different the intelligibility that they will have for a given SNRvalue will vary. As the goal is to compare real room results with those de-rived from ODEON, the same SNR values must be used in both real andsimulated room measurements. It would be expected that the intelligibilityscores measured in the real rooms would be lower than those derived fromclinical experiments, as there is no room contributing to the sound field. It


could also be expected that the ODEON-simulated rooms would generatelower intelligibility scores than the real room scores, due to simulation ap-proximations and overall perceived sound quality.

It is preferable to generate as few 0% and 100% points from the SNR val-ues as possible as it is the psychometric curve that is interesting. The SNRpoints should be within the 0% to 100% points for both the best expectedintelligibility scenario and the worst. To accommodate this, intelligibilitypoints comparitive to reference data points of 25% and 95% should be cho-sen as the range. Six different discrete SNRs for each Dantale material willbe used for the experiments.

5.2.2 Fixed Parameters

There are a number of aspects that can influence the speech intelligibilitymeasurements. The parameters with the greatest impact on the results are:

• ODEON model accuracy.

• Actual real room measurements or recorded real room measurements.

• Speech material reproduction method.

• Test subject screening.

• Presentation order.

• Speech material training.

• Measurement setup method.

ODEON model accuracy.The most important aspect of the entire experiment is the ODEON model.It is the model that generates the auralizations used for the speech intelligi-bility, so any errors in the model may also translate to the auralisations.

A prerequisite for this project was the use of professionally-made ODEONmodels. The importance of the ODEON model is too great to be left toinexperience. This naturally limits the amount of rooms that can be usedfor the comparison as both a professionally-made ODEON model and its realequivalent must be available.

Actual real room measurements or recorded real room measure-ments.The real room measurements can be carried out in either the actual room orin a listening booth using binaural recordings made from a Head And Torso


Simulator (HATS) in the real rooms. By recording the speech material in thereal room beforehand and playing the recording in a listening booth therewould be no need for the real room to be available and thus there would bemore rooms to choose from. Also, it is much easier to do the measurementsas there is no need to set the measurements up in a real room. Unfortunately,there are a lot of approximations when using a HATS and it does not allowfor head movement.

Conducting the speech intelligibility measurements in the actual room gen-erates the most accurate real room speech intelligibility results, although inpractise it is more difficult to execute. Despite the added difficulty the realroom measurements for this project will be conducted in the actual rooms.

Speech material reproduction method.The method used to reproduce the speech material is mainly dependent onthe type of material used. Dantale 1 material is typically written down andDantale 2 material is typically repeated to an operator. Written material iscorrected by an operator.

The way in which the speech intelligibility material is reproduced is of im-portance, as an operator error can occur when correcting the reproducedmaterial. Writing the material may cause spelling mistakes resulting in er-rors and when repeating the material the operator may mishear the materialresulting in an error. By writing the material down it is possiple for multipletest subjects to carry out the experiments simultaneously. However, this isnot a good option for the Dantale 2 material as writing a sentence is muchmore difficult to do in a limited time period.

Test subject screening.It is important that the test subjects are suitable for the experiment. Forthese speech intelligibility measurement comparisons it would be ill-advisedto use people with hearing disabilities. The test subjects should all be nor-mal hearing people preferably 18 years old or older. An audiogram should betaken for each test subject, dismissing any subjects with a hearing thresholdabove 15 dB HL. Also the test subjects should be able to understand thespeech material. Dantale 1 and Dantale 2 are both Danish speech materialso the subjects should have Danish as their native language. To make agood comparison there should be a reasonable number of test subjects, inorder to avoid any statistical inaccuracies. A total of 15 test subjects areneeded to produce results that have an adequate statistical accuracy. SeeAppendix B.1, page 76, for a description of the test subject screening process.

Presentation order.The order in which the material is presented can affect the outcome of the


measurements. For multiple discrete SNR values the order can be random,weighted or sequential. Presenting the material in a random order can in-fluence the results as some random orders can produce greater intelligibilitythan other random orders. This makes it a poor choice as the intelligibilityresults need to be comparable and not random.

A weighted order is a better solution, but is more complicated to executeand does not serve much purpose for these measurements. Also the ordermay appear random to the test subject, which may be confusing.

A sequential order is the best method for these measurements. If the materialis presented starting from the highest SNR value and gradually descendingto the lowest SNR value, the resulting intelligibility should then be higherthan from any other order. This makes the results very comparable as theconditions are identical for all test subjects.

Speech material training.The Dantale 2 material requires some training to fully understand and learnthe sentence that are to be repeated. This is due to the limited 50 differentwords and generic sentences that are created. Each sentence is unique butthe words used to create it are repeated. According to Wagener it takes160 sentences to fully train the test subjects, which results in a 2 dB SRTimprovement.[Wagener et al, 2003] This is obviously too many sentences totrain with as it would take over half an hour to finish. It is typical to use30 Dantale 2 sentences to train test subjects as this accounts for most ofthe training effect, while not being to time consuming. Dantale 1 does notrequire any training as the there is little training to be gained from the 200different words that are presented randomly.

Measurement setup method.The measurement setup used for the real room measurement should matchthat used in ODEON when making the auralisations. This is again to ensurethat the measurements as comparable as possible. It is important that thesource and receiver positions used for the auralisations are identical to thoseused in the real rooms. In the case of the real room measurements two loudspeakers supply speech and noise respectively, the same should therefore alsobe done in ODEON. ODEON auralises the sound files using a dermined SNR.The SNR is created digitally and should therefore be precise. However thisis not the same for the loud speakers used in the real rooms; these should becalibrated so they each produce the same SPL level to ensure the use of thecorrect SNR.


5.2.3 Chosen Measurements and Parameters

To make a thorough comparison with ODEON, intelligibility results from 15test subjects are required. Since the test subjects are paid for their time,their services can not be used for more then 90 hours in total, due to bud-getary concerns. This means that there are resources enough for six hours ofmeasurements for each test subject. The number and types of measurementsshould be chosen carefully so as to best test ODEON.

Based on the parameters mentioned and the need to have a sufficiently di-verse set of measurements with which to test ODEON, the following measure-ment program was made for both the real room and the ODEON simulatedroom measurements:

• Two different rooms, classroom 019/352 and auditorium 021/341.

• Two different receiver positions in each room.

• Two different speech materials played in each position, Dantale 1 andDantale 2 with their own noise materials.

• 6 different SNR values for each speech material.

This creates 48 different measurements. This has to be done for both thereal room measurements and the equivalent ODEON simulated room mea-surements. A total of 96 measurements is required for each test subject.

The specific discrete SNR values needed for the Dantale 1 and Dantale 2 ma-terial can be derived from the reference data for both Dantale 1 and Dantale2 material found by [Keidser, 1993] and [Wagener et al, 2003] respectively.When examining reference data for Dantale 1 it is apparent that the 25%point translates to approximately -12 dB and the 95% point is close to +3dB. When examining reference data fro Dantale 2 it is apparent that the25% point translates to approximately -10 dB and the 95% point is close to0 dB.

The SNRs used for the Dantale 1 measurements are: 3, 0, -3, -6, -9, and -12dB. The SNRs used for the Dantale 2 measurements are: 0, -2, -4, -6, -8,and -10 dB.

The positions chosen are dependent on the rooms. The relative layout of thepositions is however, similar for both rooms. The source positions for thespeech and noise are in the front of the rooms, near the blackboard facingthe seats. The receiver positions are near the front row seats to one side andin the back corner respectively.


ODEON renderings of classroom 019/352 and auditorium 021/341 can beseen in figures 11 and 12. The dimensions of each room can be seen in table2.

Figure 11: ODEON redering of classroom 019/352. Two source positions near theblackboard and two receiver positions in the seating area.

For room 019/352 position 1 is located on the 2nd row and the 2nd seat tofrom the right. Position 2 is located on the 5th row and the 1st seat fromthe left.

Figure 12: ODEON redering of auditorium 021/341. Two source positions nearthe blackboard and two receiver positions in the seating area.

For auditorium 021/341 position 1 is located on the 4th row and the 3rd seatfrom the right. Position 2 is located on the 2nd last row and 2nd seat fromthe left.

The coordinates for the source and receiver positions were measured in thereal rooms by sitting in the desired positions and measuring the appropriatedistances. The same coordinates were then used in the ODEON models.The coordinates for the sources and receivers can be seen in tables 3 and4. These are relative to the middle of the rooms from blackboard for both


Classroom 019/352 Auditorium 021/341X 9,66 m 15,96 mY 7 m 12 mZ 3 m 7,5 - 5.0 m

Table 2: Room dimensions for classroom 019/352 and auditorium 021/341. Dueto the seating area in the auditorium the height dimension Z changes.

rooms.

Speech Source Noise SourceRoom 019/352 X=1m Y=-1m Z=1.67m X=1m Y=-1m Z=1.52m

Auditorium 021/341 X=1m Y=-2m Z=1.67m X=1m Y=-2m Z=1.52m

Table 3: Speech and noise source coordinates for classroom 019/352 and audito-rium 021/341

Position 1 Position 2Room 019/352 X=4.5m Y=-1.8m Z=1.2m X=8.65m Y=1.8m Z=1.2m

Auditorium 021/341 X=7.55m Y=-3.2m Z=1.72m X=12.95m Y=2.75m Z=3.28m

Table 4: Position 1 and 2 coordinates for classroom 019/352 and auditorium021/341

5.2.4 Measurement Time

Ninty-six measurements need to be taken. Estimating that the time to doeach Dantale measurement takes 2 minutes 30 seconds, then the total mea-surement time should take 4 hours, not including breaks and the time tomeasure an audiogram.

The Dantale 1 material is written in a Dantale 1 response sheet, which con-tains enough lines and for all the Dantale words. The Dantale 1 responsesheet can be seen in Appendix L on page 116.

The Dantale 2 material is repeated and the operator then checks the answersagainst correct words in the score sheet. The score sheet can be seen in Ap-pendix K on page 114

It is important that the measurements are presented so that the subject isin no doubt as to what to do with regard to the response sheet. This not


only includes instructing the test subjects but also means that the materialmust be a user-friendly. This ensures that there is a natural flow in themeasurements without any unwanted stops. To do this it is necessary tocarry out alterations to the Dantale material.

5.2.5 Dantale track alterations

The normal Dantale tracks are not adequate for the types of measurementsthat are to be made. Alterations are made to the Dantale material, so theycan be used for the real rooms measurements as well as be prepared for theODEON auralization process. Adobe Audition 2.0 was used to edit the theDantale material.

A normal Dantale 1 track is 1 minute and 52 seconds long and a normalDantale 2 track is 1 minute 35 seconds long. The problem with the normalconstruction of the tracks is that they do not contain any pauses. Thereforethe Dantale 1 and 2 material there is no indication when the track is finished.Furthermore, there are no pauses in Dantale 2 tracks where one can repeatthe sentence material. The Dantale tracks needed to be altered to providesome natural pauses.

It was intended for the test subject to write the Dantale 1 material down ona response sheet. The response sheet contains 25 lines, one for each word inthe Dantale 1 track. There are multiple columns on several pages, one foreach track. To indicate that there is a track, and that the test subject musttherefore switch to the next column, a pause is inserted at the beginning ofeach Dantale 1 track. The pause is 10 seconds long, which should be enoughtime for the test subject to finish writing and to switch to the next column.It takes about 2 minute and 2 seconds to do one Dantale 1 measurement.

Figure 13: Real room Dantale 2 Track. The top and bottom waveform is thespeech and gated noise respectively. The noise level is higher then thespeech level, resulting in an SNR of -8 dB.


Figure 14: Simulated room Dantale 2 Track. The speech and gated noise has beenauralized resulting in a binaural recording. This track has an SNR of-8 dB, so the noise fully covers the speech signal.

The Dantale 2 tracks also needed to be altered. The same 10 second pausewas inserted at the beginning of each track to give the operator time to finishcorrecting the answers and also to turn the score sheets page if required.

The noise was also altered so is was gated instead of being a continuous noisesignal. Noise is only present from 500 ms before the sentence starts and until500 ms after the sentence is over. This leaves a 6 second pause between eachnoise burst. This pause was extended to 10 seconds which is when the testsubjects repeats the Dantale 2 sentences. The 10 second window is enoughtime to ensure that the test subjects do not get stressed. It takes about 2minute and 15 seconds to do one Dantale 2 measurement. See figures 13 and14 for Dantale 2 material waveforms for real room intelligibility material andsimulated room intelligibiliy material respectively. The noise used is gated.

It is also necessary to carry out Dantale 2 training prior to doing the Dantale2 measurements. The training material consists of 30 Dantale 2 sentences,and starts with a 10 second pause. As with the normal Dantale 2 mate-rial, the training material also uses gated noise, which starts and stops 500ms before and after each sentence. There are 10-second pauses between thenoise, which is when the test subjects repeat the sentences. It takes about 6minutes and 15 seconds to do the training track.

Once the alterations to the Dantale material were conducted, the materialwas ready to be used for the real room measurements and ready to be au-ralized for the simulated room measurements.

5.2.6 Measurement Program

It is necessary to create a general program describing which measurementsare to be made and in which order. The measurements can divided into four


main parts:

• Real classroom 019/352 measurements.

• Real auditorium 021/341 measurements.

• ODEON simulated classroom 019/352 measurements.

• ODEON simulated auditorium 021/341 measurements.

where each part has 24 measurements.

Since the intelligibility measurements used for this project are the same forboth rooms, real and simulated, the same measurement program can be usedfor each part. This also makes the order of the measurements more uniformand consequently a better basis for a comparison.

The measurement program can be seen in table 5.

The first half of the measurements is for the Dantale 1 material. The Dan-tale 1 material is first measured for position 1 where the 6 SNR values arepresented in sequential descending order. Then the Dantale 1 material ismeasured for position 2 where the same 6 SNR values are presented in se-quential descending order.

The second half of the measurements are for the Dantale 2 material. Firsta training track is used to train the test subjects for the Dantale 2 mea-surements. The training track uses randomly distributed SNR values. TheDantale 2 material is measured for position 1 where the 6 SNR values arepresented in sequential descending order. Then the Dantale 2 material ismeasured for position 2 where the same 6 SNR values are presented in se-quential descending order.

A CD is created for each of the four room situations containing Dantale 1and Dantale 2 material using the same measurement program for each room.The CDs for the real rooms contain pure Dantale material while the CDs forthe simulated rooms contain auralized Dantale material. There is 25 trackof Dantale material on each CD, where one track is a Dantale 2 training track.

Each CD contains two additional tracks; track 26 and track 27. Track 26contains 20 seconds of silence and is intended as a pause after the Dantalematerial. Track 27 contains Dantale 1 noise with an SNR of 0 dB relativeto the used speech material, which is used to calibrate the loudspeakers andheadphones for the real room measurement and simulated room measure-ment respectively. Track 27 is auralized 1 m from the speech source for the


Measurement ProgramSequence nr Speech Material Position SNR

1 Dantale 1 1 3 dB2 Dantale 1 1 0 dB3 Dantale 1 1 -3 dB4 Dantale 1 1 -6 dB5 Dantale 1 1 -9 dB6 Dantale 1 1 -12 dB7 Dantale 1 2 3 dB8 Dantale 1 2 0 dB9 Dantale 1 2 -3 dB10 Dantale 1 2 -6 dB11 Dantale 1 2 -9 dB12 Dantale 1 2 -12 dB13 Dantale 2 1 Training14 Dantale 2 1 0 dB15 Dantale 2 1 -2 dB16 Dantale 2 1 -4 dB17 Dantale 2 1 -6 dB18 Dantale 2 1 -8 dB19 Dantale 2 1 -10 dB20 Dantale 2 2 0 dB21 Dantale 2 2 -2 dB22 Dantale 2 2 -4 dB23 Dantale 2 2 -6 dB24 Dantale 2 2 -8 dB25 Dantale 2 2 -10 dB

Table 5: Measurement program for each room situation. The stated sequence isto be used for each room situation.


simulated rooms.

Based on the measurement program and the alterated Dantale tracks, eachCDs’ duration is about 1 hour and 2 minutes. This includes 24 Dantalemeasurement tracks, one Dantale 2 training track, one silent track and onecalibration track.

There are 48 different Dantale 1 measurements and 48 different Dantale 2measurements, including four 30-sentence Dantale 2 training tracks. Ideallythere would be a unique Dantale list for each of the measurements but thereare only 40 Dantale 1 lists and 16 Dantale 2 lists. Therefore it is necessary forsome of the Dantale lists to be repeated. Eight Dantale 1 lists are repeatedand all the Dantale 2 lists are repeated twice and 12 of them are repeatedthrice. It is important that the lists are not repeated in close succession toeach other, as there may be some residual memory of the list. The Dantalematerial distributed can be seen in table 27 on page 110 in Appendix G.

5.2.7 Measurement Setup

The real room measurements are conducted in the actual real room usingloudspeakers to present the speech and noise material. The general setup ofthe room can be seen in figure 15. The equipment used for the measurementscomprises:

• 2 Dynaudio BM6A loudspeakers.

• 2 Amplifiers.

• 2 HP 350D variable attenuators.

• A Revox B226 CD player.

• A speaker stand.

• A tripod with a SPL meter mount.

• A B&K Type 2240 sound pressure level meter.

• A large, solid flight case.

A flight case (H), used to transport the equipment, is placed on its side atthe source position and the speaker stand (E) is placed on top of it. Thespeakers (A) are then placed on the speaker stand pointing away from theblackboard facing the seats. One speaker is placed on the stand and thesecond speaker is placed on top of the first, but turned upside down. Thedistances from the diaphragms of the tweeters to the blackboard was 1 meteraway.


The left and right channel outputs from the CD player (D) are connectedto the two variable attenuators (B), which are then connected to two ampli-fiers (C) using the correct cables. The output from the amplifiers are thenconnected to the speakers.

Each speaker was calibrated individually by playing a Dantale 1 noise signalrelative to 0 dB SNR of the used Dantale material. The SPL from eachspeaker was measured with a B&K type 2240 SPL meter (G) at a distanceof 1 meter perpendicular to the source. The attenuators were tuned untileach speaker delivered 70 dB. The SPL meter is fastened to a tripod (F) andset at the same height as the tweeter.

Figure 15: Real room measurement setup

The simulated room measurements are conducted in a listening booth usingheadphones to present the auralized speech and noise material. A computeris used to play the CD with the auralized Dantale material. The headphonesare calibrated with an artificial ear to a level of 70 dB using Dantale 1 noiseauralized 1 m from the source. The calibration must be done for each room.

A detailed description of the measurement setups for both the real room mea-surements and the simulated room measurements can be found in AppendixB.3, page 78.

5.2.8 Measurement Procedure

There are two procedures that need to be followed when conducting the mea-surements. One is for the real room measurements and the other is for the


simulated room measurements.

Since the measurement program is the same for both real and simulatedrooms the procedural methods are almost the same for both real and simu-lated measurements. The real room measurement procedure is a little morecomplicated due to the two positions, so the test subjects need to switchpositions.

Before each measurement procedure begins the test subject is given a Dan-tale 1 response sheet to write down the Dantale 1 material.

The measurements start with the simulated rooms first. The measurementprocedure for the simulated room measurements can be found in figure 16.

Figure 16: Measurement procedure for simulated room measurements. These in-clude instructions for both Dantale 1 and 2 material and a break.

After the test subject has completed the simulated measurements, there isa short break and then the test subject and operator walks over to the cor-responding real room, where the real room measurements are to take place.The measurement procedure for the real room measurements can be foundin figure 17.

Figure 17: Measurement procedure for real room measurements. The procedureresembles the simulated room procedure and includes changing seatingposition.

After the real room procedure is finished the test subject is excused.


5.3 STI Measurements

STI measurements must be calculated for both the real rooms and for thesimulated rooms.

ODEON can generate the required STI values for each point response thatis created. ODEON can calculate two different STI values: one is based onthe impulse response and the other is based on the reverberation time. Thereal room STI values can be measured with the use of Dirac. An STI valueis needed from each source position to each receiver position. Since thereare two source positions and two receiver positions for two different rooms,then eight STI measurements need to be taken with Dirac.

5.3.1 Measurement Setup

To take the STI measurements using Dirac the proper equipment must beused. The equipment required for the Dirac measurements comprises:

• 1 Omni-directional loudspeaker with a tripod stand.

• 1 B&K Type 4192 Microphone with a tripod stand.

• 1 Laptop computer with Dirac software installed.

• 1 Loudspeaker Amplifier.

• 1 Microphone Pre-amplifier.

The general setup for the real room STI measurements can be seen in figure18.

Figure 18: STI measurement setup consisting of a laptop computer (A), an omni-directional loudspeaker (B), a loudspeaker amplifier (C), a microphone(D) and a microphone pre-amplifier (E).


The equipment is set up so the center of the omni-directional loudspeaker(B) is situated in the correct source position for every measurement. Themicrophone (D) is placed in the two corresponding receiver positions. Aloudspeaker amplifier (C) is connected to the omni-directional loudspeakerand a microphone pre-amplifier (E) is connected to the microphone. A lap-top (A) is connected to both the loudspeaker amplifier and the microphonepre-amplifier.

A test signal can be emitted to adjust the recording level for the microphone.It should be as close as possible to the red area without becoming red so asto avoid clipping.

Three signals can be used for the measurements: MLS, linear sweep or ex-ponential sweep. For this project the MLS signal was used. The length ofthe signal is also selected. A long signal ensures a better measurement. Forthis project 27 seconds were used.

The measurement begins when the when start button is clicked. During thenoise duration one should stand quite still and be quiet so as not to disturbthe measurements. After the measurements are complete the STI values arecalculated and then saved.

5.4 Pilot Test

Two pilot tests were conducted to test the measurement procedure and pro-gram to see whether any changes were required. The pilot tests were donefor both classroom 019/352 and auditorium 021/341 for both the real roomand the simulated room measurements. The full details of the pilot test canbe seen in Appendix B on page 76. The pilot test uses the same methodologyand procedure as with the main speech intelligibility experiments.

The pilot test concludes that the discrete SNRs used for both the Dantale1 and Dantale 2 material are well suited for the project. The pilot testsshowed that the Dantale 2 training tracks used for the simulated rooms weretoo difficult, they were therefore made easier. The SNRs for the simulatedrooms Dantale 2 training track were increased by 4 dB and were auralizedusing position 2 instead of position 1.

5.5 Summary

Real room speech intelligibility measurements are made for two differentrooms, classroom 019/352 and auditorium 021/341, which are compared withsimulated room intelligibility measurements created from ODEON models.


The intelligibility measurements are taken for two different receiver positionsin each room.

The speech material used for the measurements are Dantale 1 and Dantale2, using their own Dantale noise to mask the speech. Each measurement ismade from an entire Dantale 1 and Dantale 2 list respectively.

Six different discrete SNR values are used for each speech material. TheDantale 1 measurements use the SNR values: 3, 0, -3, -6, -9 and -12 dB. TheDantale 2 measurements use the SNR values: 0, -2, -4, -6, -8 and -10 dB.

The Dantale 2 training tracks use randomly-distributed SNRs for each sen-tence. The SNRs used for the training tracks are dependent on whether theyare used for the simulated rooms or the real rooms. The training tracks forthe real rooms use the SNR values: 0, -2, -4, -6, -8 and -10 dB. The trainingtracks for the simulated rooms use the SNR values: 4, 2, 0, -2, -4 and -6 dB.

Four CDs are created for each of the four room scenarios. Each CD uses themeasurement program seen in table 5. The Dantale 1 and 2 list materialsare distributed among the four CDs according to table 27 in Appendix G,page 110.

Three sets of different STI calculations are to be made for each source andreceiver position in both rooms:

• Simulated ODEON STI calculations based on the impulse response.

• Simulated ODEON STI calculations based on the reverberation timeT30.

• Real room STI calculation using Dirac.

6 SPEECH INTELLIGIBILITY RESULTS 38

6 Speech Intelligibility Results

The speech intelligibility results presented in this chapter are for classroom019/352 and auditorium 021/341. Both the measurement procedure andprogram used are described in chapter 5. The calibrated loudspeaker valuesfor each real-room measurement can be seen in Appendix J.

The results are based on measurements taken for 15 test subjects, three ofwhich were used in the project pilot test. Five test subjects were femaleand ten were male. Their ages ranged from 17-27 years. Each test subject’sintelligibility was measured on two seperate day, where the total averagemeasurement time was about 5 hours.

Results are divided between Dantale 1 and 2 material and also between posi-tion 1 and 2. The intelligibility results contain both the real room situationsand simulated rooms situations, which are compared with each other.

The results are shown as raw data, which are then fitted using equation 1from chapter 2, page 4. The results for the raw data are shown for each ofthe six discrete SNRs chosen, where the results for the psychometric curvesare spread over a wider range. The SNR range for the psychometric slopes isthe same for both Dantale 1 and Dantale 2 materials, so as to better comparethe slopes of the curves.

The raw intelligibility data is also presented as a mean value for each of thediscrete SNRs. A mean psychometric curve is created from the individualtest subjects psychometric curves, where the mean SRT and mean SRT slopevalues are used to create a mean curve. Both the mean raw data and themean psychometric curves are supplied with corresponding 95% confidenceintervals.

6.1 Classroom 019/352

6.1.1 Position 1

The intelligibility results for the Dantale 1 material in position 1 can be seenin figure 19. Results are shown for both the raw test subject data and forthe fitted psychometric curve. The psychometric curve data can be found intable 6.

The raw data shows that the real room produces higher intelligibility resultsthan the simulated room. There is a statistical difference between the realand simulated room for all SNRs except for the SNR at 3 dB. The real roomresults increase with the SNR except for the SNR at -6 dB, which decreasesfrom the SNR at -9 dB. The intelligibility differences are smallest for the


highest and lowest SNRs, where they begin to get saturated. The largestdifference is about 47% for an SNR of -9 dB.

Figure 19: Speech intelligibility for classroom 019/352, Dantale 1, position 1. Re-sults are shown for both raw data and fitted psychometric curves. 95%confidence intervals are included.

The fitted real and simulated psychometric curves are similar in shape buthave an SRT difference of 5.85 dB where the real room has the lowest SRT.

Psychometric Curve Data, Dantale 1, Position 1Data Type Real Simulated DifferenceSRT -8.42 dB -2.57 dB 5.85 dBSRT Slope 5.7 %/dB 5.5 %/dB -0.2 %/dB

Table 6: Psychometric curve data for classroom 019/352, Dantale 1, Position 1.The difference shown is relative to the real room results.


When changing the speech material from Dantale 1 to Dantale 2 it is appar-ent that there is a similar difference between the intelligibility for the real andsimulated rooms. The raw data show that the SNRs create a good likenessof a psychometric curve for both the real and the simulated rooms. There isa statistical difference between the real and simulated rooms for all the SNRs.



The fitted psychometric curves are different then those taken from position1, as they have a smaller difference in SRT which is 4.05 dB and also theslopes are much steeper. This is to be expected as Dantale 2 material gen-erally creates much steeper curves then Dantale 1. They are, however, stillvery different statistically.


Table 7: Psychometric curve data for classroom 019/352, Dantale 2, Position 1.The difference shown is relative to the real room results.

6.1.2 Position 2


The raw data from the test subjects show that the intelligibility from thereal room is generally higher then from the simulated room, where SNRs -9and 0 dB are statistically different. The simulated room does generate onepoint that is higher then the real room at a SNR of -6 but it is, however, not


statistically different. Generally the real room results, using Dantale 1 ma-terial, are smoother than the simulated room results, which are more erratic.


The fitted real room and simulated room psychometric curves are closer toeach other than those derived from position 1, but are still statistically dif-ferent, albeit not by much.

Psychometric Curve Data, Dantale 1, Position 2Data Type Real Simulated DifferenceSRT -8.46 dB -6.85 dB 1.61 dBSRT Slope 4.7 %/dB 5.1 %/dB 0.4 %/dB

Table 8: Psychometric curve data for Classroom 019/352, Dantale 1, Position 2.The difference shown is relative to the real room results.


The raw intelligibility data produced from the real room and simulated roomare very close to each other for all SNRs, where all but one SNR is statisti-cally similar. The general appearance of the raw data is two smooth curves,where the simulated room results are slightly lower than the real room re-sults.


Figure 22: Speech intelligibility for Classroom 019/352, Dantale 2, position 2.Results are shown for both raw data and fitted psychometric curves.95% confidence intervals are included.

The fitted mean psychometric curves for the real and simulated rooms arevery close and not statistically different. The real room generates a lowerSRT, however the simulated room has a higher slope.


Table 9: Psychometric curve data for classroom 019/352, Dantale 2, position 2.The difference shown is relative to the real room results.

6.2 Auditorium 021/341

6.2.1 Position 1


The raw data shows that the real room generates a higher intelligibility thanthe simulated room. The simulated room results are much lower than the


real room results. There is a statistical difference for all six SNRs, fluctuat-ing between about 13 % and about 36 %. The simulated raw data resultsappear to create a flatter curve than the real results.

Figure 23: Speech intelligibility for auditorium 021/341, Dantale 1, position 1.Results are shown for both raw data and fitted psychometric curves.95% confidence intervals are included.

As this the raw data, the fitted psychometric curves for the real room andthe simulated room are also statistically different. There is a large differencein the SRT of 7.02 dB and the simulated rooms curve is much flatter thenthe real rooms curve, which coincides with the raw data observations.

Psychometric Curve Data, Dantale 1, Position 1Data Type Real Simulated DifferenceSRT -6.12 dB 0.90 dB 7.02 dBSRT Slope 5.0 %/dB 4.1 %/dB -0.9 %/dB

Table 10: Psychometric curve data for auditorium 021/341, Dantale 1, position1. The difference shown is relative to the real room results.


The raw data shows that there are similar results when changing from Dan-tale 1 to Dantale 2 material. There is a large difference between the real andsimulated rooms for all SNRs, all of which are statistically different. The


smallest difference is about 14% and the largest difference is about 37%.


The psychometric curves created from the raw data are very similar in ap-pearance but the real room curve has a lower SRT than the simulated roomcurve. The two curves are statistically different.


Table 11: Psychometric curve data for auditorium 021/341, Dantale 2, Position1. The difference shown is relative to the real room results.

6.2.2 Position 2


The mean raw data generated from the simulated room and real room arevery close to each other. There is however a large difference for an SNR of-6 dB. There is no statistical difference between the real room and simulated


room results for all SNRs except the SNR of -6 dB. Three of the SNRs gen-erate results where the simulated room has the highest intelligibility thoughnone of them are statistically different from the real room results.


The corresponding psychometric curves for the real room and simulated roomare very close to each other, where the difference in SRT is less than 1 dB.There is no statistical difference between the two SRTs. The simulated roomscurve has a steeper slope then the real rooms. The large difference presentin the raw data for a -6 dB SNR is not apparent in the curve.

Psychometric Curve Data, Dantale 1, Position 2Data Type Real Simulated DifferenceSRT -4.67 dB -3.73 dB 0.93 dBSRT Slope 3.7 %/dB 4.3 %/dB 0.6%/dB

Table 12: Psychometric curve data for auditorium 021/341, Dantale 1, Position2. The difference shown is relative to the real room results.


The mean raw data results for the real room and simulated room are similar.For SNRs of -10 and -8 dB there is no difference. For the remaining SNRs


there appears to be a fairly constant difference of about 10%. There is nostatistical difference between the real room results andthe simulated roomresults for all SNRs.


The mean psychometric curves generated from the raw data for both the realroom and simulated room are almost identical. The real room has a slightlysmaller SRT but it is not statistically different from the simulated room’sSRT.

Psychometric Curve Data, Dantale 2, Position 2Data Type Real Simulated DifferenceSRT -6.05 dB -5.15 dB 0.90 dBSRT Slope 13.7 %/dB 11.3 %/dB 2.4 %/dB

Table 13: Psychometric curve data for auditorium 021/341, Dantale 2, position2. The difference shown is relative to the real room results.

7 SPEECH TRANSMISSIONS INDEX RESULTS 47

7 Speech Transmissions Index Results

The STI was calculated for the both classroom 019/352 and auditorium021/341 for both the real rooms and ODEON-simulated rooms. The realroom STI calculations were measured using the Dirac software for each com-bination of the source and receiver positions. The simulated rooms STIcalculations were derived from ODEON’s point responses for each combina-tion of the source and receiver positions.

The STI values for classroom 019/352 and auditorium 021/341 were mea-sured and are displayed in tables 14 and 15.

Room Classroom 019/352Position Position 1 Position 2Source Speech Noise Speech NoiseODEON STI 0.75 0.75 0.75 0.74ODEON STI T30 0.66 0.72 0.73 0.74Dirac STI 0.75 0.77 0.76 0.76

Table 14: Classroom 019/352 STI results. ODEON STIs calculated from im-pulse response and reverberation time T30. Real room STI derivedfrom Dirac.

The classrooms STI values based on the impulse response are very constantwith no significant difference between them. The STI values based on theT30 reverberation time are however not very constant; the STI values in po-sition 1 seem to deviate from those in position 2 and from the STI valuesbased on the impulse response.

For the classroom, the STI based on the reverberation time is significantlylower then the STI based on the impulse response from the speech sourceto position 1, where the difference is 0.09. There is also a small differencein the STI from the noise source to position 1, where the STI based on thereverberation time is 0.03 lower.

The auditorium STI results derived from ODEONs calculated impulse re-sponses and reverberation times are very similar, but the STI based on thereverberation time is slightly lower then the STI based on the impulse re-sponse.

The auditorium STI results for position 2 are slightly higher than in position1 for the impulse response results, where the reverberation time results areconstant for both positions.


Room Auditorium 021/341Position Position 1 Position 2Source Speech Noise Speech NoiseODEON STI 0.51 0.51 0.52 0.52ODEON STI T30 0.50 0.50 0.50 0.50Dirac STI 0.53 0.53 0.51 0.51

Table 15: Auditorium 021/341 STI results. ODEON STIs calculated from im-pulse response and reverberation time T30. Real room STI derivedfrom Dirac.

The real room STI results created by Dirac are similar to those created byODEON. however, for the real room the STI is slightly higher in position 1.

The real room Dirac measurements show that the STI for each of the sourcesand positions are close to those generated by ODEON’s impulse response forboth the classroom and the auditorium.

Based on the low T30 STI values for position 1 in classroom 019/352 a furtherinvestigation of the STI surrounding the speech source has also been carriedout. This was executed by creating several new source positions, with whichto create new STI measurements for position 1. Six additional source pointswere created, each is 15 cm from the speech source position travelling alongeach axis. They all measure the STI values for position 1 only. This has onlydone using ODEON, Dirac measurements were not created for this investiga-tion. The results from the additional source positions can be seen in table 16.

ODEON STI Classrom 019/352 position 1Source position STI STI T30

Speech source 0,75 0,6615 cm below 0,75 0,7215 cm above 0,76 0,7515 cm left 0,74 0,7515 cm right 0,78 0,7215 cm in front 0,74 0,7115 cm behind 0.79 0.73

Table 16: Additional STI results using the speech sources surrounding positionsfor the simulated classroom 019/352 in position 1. 15 cm below corre-sponds to the noise source.


The results show that the speech source position generates the lowest T30

based STI value compared to all six surrounding source positions by at least0.05. The impulse reponse STI from the positions surrounding the speechsource are similar except for "15 cm right" and "15 cm behind", which areslightly higher.

Both simulated rooms’ STI has been mapped using ODEON for a heightof 1.2 m, which can be seen in Appendix D, page 99. There the STI iscalculated based on the impulse responses. The results are shown for boththe speech and noise source.

8 DISCUSSION 50

8 Discussion

In this chapter the results from the speech intelligibility measurements andthe STI measurements are evaluated and discussed. Possible explanationsfor the results are also discussed.

8.1 Speech Intelligibility

The speech intelligibility psychometric curves derived from ODEON aural-izations are statistically lower in position 1 for both rooms using both speechmaterials. The speech intelligibility is also statistically lower for position 2in the classroom using Dantale 1 material. This means that for 5 out of 8psychometric curves are the intelligibility results measured are statisticallydifferent. Similar results are noticed from the raw intelligibility data, where28 of 48 real room intelligibility measurements are also statistically lowerthan the equivalent simulated rooms. A comparison of the mean psychome-tric curves for the classroom and the auditorium can be seen in figures 27and 28 respectively.

When examining the real room speech intelligibility results for both theclassroom and the auditorium it is apparent that the speech intelligibility ishigher in position 1 and lower in position 2. This is to be expected basedon basic room acoustic theories. Although the difference in intelligibility be-tween the two receiver positions is not large it is definitely noticeable. Thisis very reasonable and is to be expected.

The ODEON simulated rooms however, generate speech intelligibility resultsthat are lowest in position 1 and highest in position 2. There is a large dif-ference in intelligibility between position 1 and position 2 for both the roomsmodeled. This is rather unexpected as the intelligibility should be lower ata greater distance from the source.

It is clear that the simulated rooms intelligibility results deviate much morefrom the real room results for position 1 than in position 2. In fact, the rela-tive locations of the curves for the classroom and auditorium are remarkablysimilar to each other. They are, of course, not comparable to each other butit is, however, an interesting observation that may give an indication to thecause of the deviations.

It is curious that the same differences between the real room and simulatedroom measurements are present in both the classroom and auditorium asthe two rooms are rather different in shape and size. The general layout ofthe source and receiver positions are comparable but the actual positions arevery different. Despite having very different scales, the shapes of the room

8 DISCUSSION 51

Figure 27: Mean speech intelligibility curves for classroom 019/352.

Figure 28: Mean speech intelligibility curves for auditorium 021/341

8 DISCUSSION 52

are also different; the classroom is basically a simple box shape and the au-ditorium is more trapeze shaped. In the classroom the receiver positionsare located on the same vertical position, where as in the auditorium thereceiver positions are located at different heights. For simulated rooms, thiscould lead to the conclusion that the speech intelligibility improves whenpositioned further away from the source. This does not explain why theauditorium’s position 1 is affected by very low speech intelligibility resultswhen the classrooms position 2 is not affected by low intelligibility as theyare both at similar distances from the source. The reason for this could bedue to the relative closeness to the source rather than the absolute closeness.

The lowest measured intelligibility results are all for the simulated rooms inposition 1. These are the positions that are measured first during each ofthe measurement days, so it is natural to consider whether any sequentialorder effects influenced the results. This does not seem likely, however, asthere is a relatively easy training track for the Dantale 2 material and theDantale 1 material does not require any training. Also, on the second day ofmeasuring the test subjects are very well aquainted with both the Dantale1 and Dantale 2 material. The order in which the rooms are measured alsovaries and the results show no significant difference between the order.

It is also possible to hear that the speech material is simply harder to un-derstand in position 1 then in position 2. This is best done by listening totwo identical speech materials auralized for both position 1 and position 2using the same SNR. There are less high frequency cues in position 1 thanin position 2. The sound also seems slightly less clear in position 1.

The quality of the auralizations are also questionable, as they do not soundquite like the real rooms, but rather slightly synthetic. This perceived soundquality difference could account for the lower intelligibility differences as thesound is simply different.

The added information concerning the STI for the two positions could helpexplain the differences in intelligibility.

8.2 STI

There are a few discrepancies for some of the STI results.

The STI measurements obtained from ODEON, based on the impulse re-sponse and the T30 reverberation time, show some variation between the tworesults for the classroom in position 1. There the STI based on T30 is consid-erably lower then the STI based on the impulse response. For the speech theT30 STI is 0.66 and the impulse response and Dirac STI are both 0.75. This

8 DISCUSSION 53

could indicate that ODEON calculates the reverberation time to be largerthen it actually is and therefor creates a low STI based on this.

For the classroom the STI values obtained from ODEON’s impulse responsecoincide with the STI results measured with Dirac. With a STI of about0.75 this seems to be quite reasonable for such a small room. The STI basedon the T30 reverberation time is however not reasonable for the speech inposition 1 and is most likely incorrect.

For the auditorium the STI values obtained from ODEON are very close tothose measured with Dirac. The Dirac STIs are however slightly higher.

The STI values for the auditorium are around 0.52. This seems reasonableas the auditorium is much bigger then the classroom and therefore shouldhave a lower STI value. It is also easy to hear that speech generally is easierto hear in the classroom rather than the auditorium.

The STI derived from ODEON’s impulse response is very close to the STIthat Dirac calculates for the real rooms. This could indicate that ODEON’simpulse response STI accurately represents the speech intelligibility for eachposition, but that the corresponding auralized speech material is not accu-rately represented by ODEON’s STI.

The STI derived from the T30 reverberation time could explain the low speechintelligibility results obtained from position 1 in the classroom. ODEONstates that the STI from the speech source to position 1 is 0.66 where theSTI from the noise source to position 1 is 0.73. This is a large differenceconsidering that the two source positions are only 15 cm apart. If the au-ralizations created are more representative by the T30 STI than the impulseresponse STI than the speech may become additionally masked by the noisedue to the STI differences.

When examining the STI values obtained from the additional source po-sitions surrounding the speech source, it appears that the speech source,located in the center, is the worst position when comparing T30 STI values.This may just be an unfortunate source position for ODEON, where thepoint response is not adequately calculated with respect to the T30 STI.

8.3 ODEON

The reason for the differences in speech intelligibility for the real and sim-ulated rooms could be as simple as "ODEON just models the rooms incor-rectly". To try to get a better understanding of the intelligibility results anexpert opinion was required.

8 DISCUSSION 54

A meeting with Jens Holger Rindel and Claus Lynge from ODEON was in-stigated to discuss the intelligibility results measured for both the rooms.Jens Holger Rindel and Claus Lynge are the creators of the room modelsused for this project and are therefore well acquainted with models. Theyare considered to be leading experts concerning ODEON.

They were asked about the large intelligibility differences in position 1 andwhy the same difference is not present in position 2 for both rooms. Theyexamined the ODEON setup used for the measurements and concurred thatthe general setup used was correct. They also examined the method used tocreate the auralizations which was also accepted.

After having listened to some of the auralized speech material for the class-room and auditorium for both positions, as well as the impulse responsesthat ODEON generates, they presented a few theories that could potentiallyexplain the discrepancies.

For the classroom they made a few observations and had the following theoryto explain the two positions difference in intelligibility.

Based on listening to the impulse response and reviewing of the parametersthat ODEON creates from each point response, they ultimately detected flut-ter echoes present in position one. The flutter echoes could be heard whenlistening to the auralized sound material, although they were not dominant.They also examined position 2 and concluded that there were no echoespresent. They explained that ODEON may overcompensate for the flut-ter echoes in position 1 and therefore the resulting speech intelligibility wasworse than it actually is in the real room. The real room does contain flutterechoes but these are only apparent when generating a Dirac impulse 1, andnot really noticeable when listening to speech. When comparing the speechmaterial in the real room with the auralized speech material it is apparentthat the flutter echoes are more noticeable in the auralized material.They stated that the flutter echo could possibly be controlled by increasingthe scattering coefficient for the materials used in the ODEON model. In-creasing the number of rays used to create the point responses could alsohelp.For the auditorium they also developed a theory based on listening to theauralized sound files and impulse responses. The impulse response showedthat there were no flutter echoes present in either position 1 or position 2.But after reviewing the auralizations for both position 1 and 2 they coulddetect a slight echo in position 1. They stated that there was no echo present

1This can be created by simply clapping your hands

8 DISCUSSION 55

in the auralized sound files for position 2.

As with the classroom they stated that the echoes could be a result of a tosmall scattering coefficient or by not having enough rays.

There is almost always a solution to rectify any acoustical discrepanciesthat might occur when modeling in ODEON by changing the parametersto compensate for the results. The problem with that solution is that inthe real world people who use ODEON generally do not have the luxury ofhaving real room results with which to compare. They must rely solely onthe model they use, and there is no guarantee that the results are accurate oreven close. This is the main reason why the prerequisite for this project wasto only use professionally made ODEON models, as it best reflects a real lifescenario. However, this is not entirely true, as the two models used for thisproject were subjected to many tests through the development of ODEONand were tested against real measurements and thereby also optimized to beas accurate as possible.

9 CONCLUSION 56

9 Conclusion

Based on the speech intelligibility results seen in chapter 6, the STI resultsseen in chapter 7 and the assessments and discussions of the results in chap-ter 8 the following conclusions are made.

• ODEON auralizations generate lower speech intelligibility values thanthose produced by equivalent real room speech intelligibility measure-ments. 5 out of 8 psychometric curves and 28 out of 48 discrete SNRvalues produce intelligibility results, where the real rooms are statisti-cally higher than the ODEON simulated rooms.

• The intelligibility differences between real rooms and simulated roomsare not constant, but dependent on position. The closer the positionwas to the source the greater the difference in intelligibility became.

• Receiver positions auralized with an ODEON model containing audibleechoes have the greatest intelligibility difference.

While this is not a large scale investigation the results clearly show, thatthe speech intelligibility from ODEON-simulated rooms are lower than theequivalent real rooms. When conducting speech intelligibility measurementsfrom an ODEON simulated room, it is likely that the speech intelligibilitymeasured is lower then that of a real room equivalent.

10 FUTURE DEVELOPMENT 57

10 Future Development

This project identified that there can be large differences in intelligibilitywhen comparing real room speech intelligibility measurements to ODEONsimulated room intelligibility measurements. The largest deviation occurs inposition 1 for both the classroom and the auditorium.

A more thorough investigation of one of the rooms could be a good idea. Itcould be interesting to attempt to map the intelligibility for a single roomusing only one speech material but for several more positions. The area of in-terest is mostly around position 1, but it could be interesting to see whetherthe speech intelligibility increases steadily from position 1 to position 2.

The Dantale 1 material can create a slightly erratic results due to the differ-ence in intelligibility that each list generates. Dantale 2 would be preferablesince it creates a more homogeneous intelligibility.

By reducing the range of measurements to only one room and one speechmaterial, there is more time to measure a lot more positions. By utilizing thesame measurement program and procedure used in this project, the positionsalready measured need not be repeated. Each position should still use thesame six SNR values as in this project.

10 FUTURE DEVELOPMENT 58

Acronym List

This report uses the following acronyms:

B&K Brüel & KjærBNC Bayonet Nut ConnectionCAHR Center for Advanced Hearing ResearchCD Compact DiscDirac Dual Input Room Acoustics CalculatorDTU Danmarks Tekniske UniversitetHATS Head And Torso SimulatorHearCom Hearing in the Communication SocietyHL Hearing LossHRTF Head Related Transfer FunctionMLS Maximum Length SequenceMTF Modular Transfer FunctionRASTI Rapid Speech Transmission IndexSNR Signal to Noise RatioSPL Sound Pressure LevelSRT Speech Reception ThresholdSTI Speech Transmission Index

REFERENCES 59

References

[Elberling et al, 1989] C. Elberling, C. Ludvigsen, P.E. Lyregaard (1989),DANTALE: A new Danish speech material, Scandinavian Audiology 18,page 169-175.

[Hagerman, 1984] B. Hagerman, (1984), Some Aspects of Methodalogy inSpeech Audiometry - Studies of reliability, computer simulations anddevelopment of a new speech material for measuring speech receptionthreshold in noise, Scandinavian Audiology, supplemental 21.

[Keidser, 1993] G. Keidser (1993), Normative data in quiet and noise forDANTALE - a Danish speech material, Scandinavian Audiology 22,page 231-236.

[Poulsen, 2005] T. Poulsen, (2005), Acoustic Communication - Hearing andSpeech, Lecture note 31230-5, Ørsted DTU, Denmark.

[Wagener et al, 2003] K. Wagener, J.L. Josvassen, R. Ardenkjær (2003), De-sign, optimization and evaluation of a Danish sentence test in noise,International Journal of Audiology 42, page 10-17.

[IEC 60318-1, 1998] IEC 60318-1 (1998), Electroacoustics - Simulators of hu-man head and ear - Part 1: Ear simulator for the calibration of supra-aural earphones, International Electrotechnical Commission., Geneva.

[IEC 60318-2, 1998] IEC 60318-2 (1998), Electroacoustics - Simulators of hu-man head and ear - Part 2: An interim acoustic coupler for the cali-bration of audiometric earphones in the extended high-frequency range,International Electrotechnical Commission., Geneva.

[IEC 60645, 2001] IEC 60645 (2001), Electroacoustics - Audiological equip-ment - Part 1: Pure tone audiometers, International ElectrotechnicalCommission., Geneva.

[ISO 389-8, 2005] ISO 389-8 (2005), Acoustics - Reference zero for the cali-bration of audiometric equipment - Part 8: Reference equivalent thresh-old sound pressure levels for pure tones and circumaural earphones, In-ternational Organization for Standardization, Geneva.

[ISO 389-9, 2007] ISO/DIS 389-9 (2007), Acoustics - Reference zero for thecalibration of audiometric equipment - Part 9: Preferred test conditionsfor the determination of reference hearing threshold levels, InternationalOrganization for Standardization, Geneva.

[ISO 8253-1, 1989] ISO-8253-1 (1989), Acoustics - Audiometric test methods- Part 1: Basic pure tone air and bone conduction threshold audiome-tery, International Organization for Standardization, Geneva.

REFERENCES 60

[Zwicker&Fastl, 1999] E. Zwicker, H. Fastl (1999), Psychoacoustics, Factsand Models, Springer.

A MEASUREMENT PARAMETER CONSIDERATIONS 61

Appendices

A Measurement Parameter Considerations

The parameters mentioned in this Appendix are described knowing that theend results should be a good comparison of speech intelligibility measure-ments for real rooms with speech intelligibility measurements from ODEON-simulated rooms. Here all relevant parameters and options regarding thespeech intelligibility measurements are contemplated and discussed. As-pects concerning the variable and fixed parameters are described as wellas any comciderations concerning ODEON.

A.1 Speech Intelligibility Measurement Setup

There are two different measurement setups used to measure the speech in-telligibility for this project as half of the measurements are from real roomsand the other half are from simulated rooms. The simulated measurementswould most likely take place in a listening booth, whereas the real measure-ments could potentially be made in either the actual room or via headphonesin a listening booth using binaural recordings.

A.1.1 Simulated Room Measurements

ODEON can theoretically create rooms that have the same acoustical char-acteristics as any given room. This means that the rooms modeled should beidentical to the real rooms if they are modeled correctly. This makes speechintelligibility measurements easy to perform, as once the model is created,source and receiver positions can be selected to be identical to these of thereal room measurements. The resulting auralisation is then played thoughheadphones to the subjects in a listening booth.

The advantage of modeling the rooms in ODEON is the immense flexibil-ity and ease in creating different situations. Once auralisations are created,they can be saved and played later for the test subject at any time that isconvenient.

The disadvantage of modeling the rooms in ODEON is that the resultingauralisation is only as good as the model that is created. If the model istoo simplistic or if the materials chosen are incorrect, then the auralisationwill suffer. There are other restrictions such as head movements for binaurallistening, which the auralisation cannot take into consideration.


A.1.2 Real Room Measurements in Actual Rooms

One approach to conducting the speech intelligibility measurements in thereal rooms could be to have test subjects sit in the actual rooms at a givenposition. There they could undergo the speech intelligibility measurementsby listening to speech material masked by noise played through loudspeakers.

The advantage of this method is that it is the most accurate situation inwhich to measure the intelligibility of the room, since it is the actual realroom and could therefore be described as the perfect condition. Assumingthat the same uniform procedure is used for both simulated and real roommeasurements, the only parameters that could influence the outcome of thesemeasurements would be environmental conditions such as background noise,heat, light and room size.

There are, however, some issues regarding the real rooms measurements,which may influence the choice of this method. The issues are more of apractical nature, such as room availability and measurement setup whichcould be a deterrent to using real room measurements in actual rooms.

A.1.3 Real Room Measurements using Binaural Recordings

A way of ensuring that the environmental conditions present are the sameas those used in the listening booth would be to use a HATS to record thematerial at a desired position and later present it to the test subject in thelistening booth. This will garantee that exactly the same sound is heard byall the test subjects, as the same recordings are presented.

Using a HATS has the added advantage of simplifying the measurementprocess as both simulated and real room measurements could be presentedin the same booth. This also eliminates any room availability issues theremay be.

A.2 Variable Parameters

In order to validate ODEON it is important that the results are not leftentirely to chance. Having one measurement to describe ODEON is obvi-ously too little and would ultimately be a random result, therefore severalmeasurements are required. Ideally there would be many different instancesof each parameter in order to conduct a massive comparison with ODEON,but that is not realistic due to the lack of resources. It is important toidentify which variable parameters are crucial to the comparison and whichparameters are not.


The parameters of interest in this project, that may have multiple instancesare:

• Rooms

• Source and receiver positions

• Speech material

• Interfering noise

• Signal-to-noise-ratios and adaptive/static method

A.2.1 Rooms

Having several rooms, with which to compare speech intelligibility measure-ments, is very important for several reasons. The first reason is that onlyhaving one room is not very representative of how ODEON performs in gen-eral. With only one room the results rely entirely on that one model, whichmay produce very similar or very non-similar results when compared to thereal room measurements. It would not be a fair assessment of ODEON onlyto rely on one model.

Having several models has the added benefit of being able to test roomswith different complexities. There is obviously a great difference between asimple rectangular room and a fan-shaped concert hall. By utilizing thesecomplexity differences it is possible to find similarities and discrepanciesbetween the models to better judge ODEON.

A.2.2 Source and Receiver Positions

The positions are used for the speech intelligibility measurements are notunimportant, especially since it is only realistically possible to carry out alimited number of combinations. For clinical use speech intelligibility is oftenmeasured from a very limited transmission line, namely the distance from theheadphones to the eardrum, where both speech and noise are mixed. Sincethis project uses the intelligibility in rooms it is important to use source andreceiver positions that create a proper sound field describing the acousticsof the room. If a source and receiver are too close together the direct soundwill drown out any reflections that might contribute to the sound field at thesource, which is not a good way to test the room. An appropriate distancefrom source to receivers would be above 3 m for this kind of measurement.

The locations for the source and receivers are less important, as potentiallyany sound transmission from one point to another could be interesting, butfor multiple receiver points it is a good idea to have very different locations.


This could be achieved by having multiple receiver points distributed evenlyin the room with one source, thereby creating a different sound image foreach position.

The position of the noise source with respect to the speech source is crucialto the SNR values received at the receiver point. The noise source creates itsown sound field and will therefore change depending on the receiver position,which is also true for the speech source. Having different fixed positions forboth the speech source and noise source could create an SNR mis-match ifthe distance from the noise source to the receivers differs from the distancefrom the speech source to the receivers. This means that both the noiseand the speech sources should always have the same relative distance to thereceiver point. The only real way to do this would be to have the noise andspeech sources at the same location. That way their respective distanceswould always coincide and the SNR will remain the same.2 For practicalpurposes this can be difficult to achieve except for the case where the sameloudspeaker generates both speech and noise. It is possible to approximatethis setup by having the noise and speech source very close to each otherpreferably on a perpendicular axis to that of the distance to the receiver.In this way the relative speech and noise source distance decreases as thedistance to the receiver increases.

A.2.3 Speech Material

Having several speech materials could be interesting for this project as allthe speech materials are different and there could potentially be a differencewhen ODEON auralizes the material.

When choosing the speech material one also chooses which nationality thetest subjects are to be and vice versa. Since the measurements are conductedin Denmark it natural to use Danish speech material. There are several Dan-ish speech materials which are widely used. Dantale 1 and 2 are most oftenused in clinics and are also very often used at DTU. Speech materials suchas HINT could also be used, but for simplicity it is easier to use two Dantalematerials as they are constructed along similar lines.

It may be interesting to test the effect of different types of speech materialsfor the rooms. Dantale 1 consists of single words while Dantale 2 is made upof five words to create a coherent sentence. The length of the speech mate-rial is therefore an important factor with regard to speech intelligibility. Itis easier to miss/mishear a single word than it is to miss/mishear an entire

2This is true for use in an anechoic chamber, where no sound field other than the directsound is present. Depending on frequency characteristics for both speech and noise thedispersion of sound may vary and a different SNR may be present at the receiver position.


sentence assuming the same SNR in both situations.

The rooms’ acoustical characteristics can also contribute to the outcomeof the speech intelligibility depending on the speech material. In a highlyreverberant room it is plausible that the reflections from a sentence maymask some of the remaining sentence thus making it harder to understand,whereas a single word will not mask itself.

A.2.4 Interfering Noise

Choosing the noise to be used for the speech intelligibility measurements alsohas some importance. The type of noise used could be anything, for exam-ple, white noise, pink noise, speech shaped noise, multitalker noise and so on.

One could argue that the type of noise used does not matter as long as thesame noise and procedure are used consistently throughout the experiments,so that the end results are comparable. However, since it is the intricaciesof the room that reflect and absorb the noise, which are dependent on fre-quency, it is possible that the speech may be poorly masked in one roomand well masked in another if the noise frequency characteristic differs fromthe speech. An upward spread of masking can also occur, so it is not neces-sarely the the same frequencies that mask the speech.[Zwicker&Fastl, 1999]This can lead to a confusing comparison if multiple rooms or positions arechosen. On the other hand, if the frequency characteristics are the samefor both the noise and the speech then one could expect a more constantmasking in both the real and the simulated rooms.

Dantale 1 and Dantale 2 speech intelligibility material is supplied with Dan-tale 1 and 2 noise respectively. The Dantale 1 noise is created from whitenoise, which is speech spectrum-shaped and amplitude-modulated to givean approximate spectrum equal to the speech. The noise for Dantale 2 iscreated from superimposing the Dantale material many times until it is per-ceived as being noise rather than speech. This means that the Dantale 2noise has the same frequency spectrum as the speech since it is comprised ofthe same material.

A.2.5 Signal-to-Noise Ratios and Adaptive/Static Method

The signal-to-noise ratios used for the measurements depend on whether anadaptive method or a static method is used. The adaptive method typicallyused for the Dantale 2 material produces intelligibility around 40% and 60%by altering the SNR depending on previous answers. This creates a quickmethod for generating an estimated SRT based on relativly few random SNRvalues. While this is good for quickly generating an SRT, the lack of mea-


surements can make it less accurate as other intelligibility points are notexamined.

Using a fixed number of SNR values for the measurements forces the testsubjects to complete exactly the same measurements/conditions, which íswell suited for a comparison. The number of SNRs used is also important asa greater number of SNRs will produce a better basis for comparison as wellas potentially creating descriptive psychometric curves without fitting thedata. The resulting fitted psychometric curves will also be more accurate asthey are based on more points.

The problem with specifying the SNR value beforehand is that, due to thenature of subjective measurements, the test subjects’ range from 0% intelli-gibility to 100% intelligibility can be very different.3 But since both Dantale1 and Dantale 2 are rather well documented speech materials one can esti-mate an appropriate range for the SNR values.

Due to the wish to compare results with ODEON, the same SNR values mustbe used in both real and simulated room measurements. It is to be expectedthat the intelligibility scores measured in the real rooms would be lower thanthose derived from clinical experiments, as there is no room to contribute tothe sound field. It could also be expected that the ODEON-simulated roomswould generate lower intelligibility scores than the real room scores, due tosimulation approximations and overall perceived sound quality. This meansthat the range of SNR points should be within the 0% to 100% point forboth the best expected intelligibility scenario and the worst. To accommo-date this, intelligibility points comparitive to reference data points of 25%and 95% have been chosen as the range.

When examining reference data for Dantale 1 from [Keidser, 1993] it is ap-parent that the 25% point translates to approximately -12 dB and the 95%point translates to +3 dB.

When examining reference data for Dantale 2 from [Wagener et al, 2003] itis apparent that the 25% point translates to approximately -10 dB and the95% point translates to 0 dB.

At least four different SNR values should be distributed evenly between eachrange. This is so as to have enough points to adequately cover the large rangeof intelligibility, that the test subjects will have and also to more accurately

3Depending on the speech material some 100% intelligibility points are never found.This is, of course, dependent on the speech material and the test subject. Test subjectscan occasionally mishear unmasked speech material, which will result in an intelligibilityscore that is less than 100%.


describe the intelligibility measured. More measurements will create a finerresolution but will also increase the measurement time.

A.3 Fixed Parameters

Many parameters influence intelligibility measurements. It is important thatthese parameters are used for both the real and simulated measurements.Some of the parameters are crucial to the foundation of the measurementsand should be decided upon in order to create a uniform method for boththe real-room and simulated-room measurements.

The fixed parameters that this project will focus on are:

• Speech material reproduction

• Binaural hearing/HATS

• Test subjects

• Presentation order

• Training

• Setup method

• Environmental conditions

A.3.1 Speech Material Reproduction

In order to determine the speech intelligibility of a test subject it is necessaryfor the subject to reproduce the material for the operator. There are twomain ways of of doing this.

One way of measuring the speech intelligibility is to have the test subjectswrite the material down, which is then later corrected by the operator. Theadvantage of this method is that many subjects can listen to the same ma-terial at the same time. This parallelizes the measurements making themmore efficient and is therefore suitable for many subjects with many posi-tions. The disadvantage is the writing limitations. If the material is singlewords then there is a good chance that the subject is unaffected by writing,but if the material is sentences or other multiple word material then it maybe more stressful and difficult to write.

Another method is to have the subjects repeat speech material and the opera-tor then assesses the answer and ultimately the intelligibility. The advantageof repeating the material is that it is a sure way of measuring the intelligibil-ity without having to worry about writing problems or the added stress of


having to write one or several words. The disadvantage is that it is mainlysuited for one test subject at a time, which could be cumbersome if there aremany subjects each with many scenarios that need measuring. There is alsothe added element of the operator, who may have misheard the test subject,resulting in an inaccurate intelligibility.

A.3.2 Binaural Hearing/HATS

To simplify the process of the real life measurements in real rooms it is pos-sible to create binaural recordings of the speech material using a head andtorso simulator (HATS). This means that instead of having the test subjectssit in the actual rooms listening to the speech material with noise, a HATScan be used to record the same sound that the test subject would otherwisehave listened to.

This has the advantage of not requiring the actual real rooms for each of thetest subject’s measurements as they then can be carried out in a listeningbooth along with the simulated room auralisations.

The disadvantages of using the HATS is that it is in itself an approximationof a human head, torso and ears so the Head Related Transfer Function(HRTF) would not necessarily be the same as that of the test subject andwould, therefore, not fully represent the actual real room sound. There isalso the added disadvantage of not being able to move the head as a normalperson would. Having full head mobility is a quality that helps people reachan optimal SNR when listening to speech; using a HATS would eliminatethis assistance.

A.3.3 Test Subjects

Choosing the right test subjects can be critical for any type of measurementsas they should have similar qualities relevant to the study. In this case thestudy is about speech intelligibility so language and vocabulary are impor-tant since the speech material is either single words or whole sentences. Thetest subjects’ native language should match that of the speech material. Inthis case the native language should be Danish since the project takes placein a Danish university with mainly Danish students.

Age is also an issue since young peoples’ vocabulary is not as developed asadults’, and they may also lack the concentration skills required to fulfill theexperiment. Typically, test subjects should be at least 18 years old. Therecan be an upper age limit as there may be problems using people over theage of 60 as test subjects since their cognitive abilities may have deterio-rated, which can potentially influence the experiment. Older people may


also lack the stamina to fully concentrate during the entire duration of themeasurements.

Equally important is the test subject’s hearing, which again depends on thetype of experiment. Normally test subjects are distinguished between hav-ing normal hearing or being hearing impaired. Normal hearing people willtypically be within the ±15 dB HL range.

For this type of speech intelligibility experiment it would be natural to usepeople with normal hearing who are 18 years old or older, and whos nativelanguage corresponds to that of the speech material.

A.3.4 Training

Some of the material may require that the test subjects undergoe some train-ing with the material before conducting the actual experiment. This is truefor material such as Dantale 2, where each track of sentence-based materialis comprised of the same 50 words. During an experiment the test sub-ject gradually becomes more adept at recognizing the speech material andconsequently scores a higher speech intelligibility. To compensate for thisWagener [Wagener et al, 2003] uses 160 sentences to train the test subjects,which results in a 2 dB SRT improvement. Obviously 160 sentences is toomany to use as it would take over half an hour to complete the trainingsession. For clinical use 30 Dantale 2 sentences are typically used to traintest subjects, as this accounts for most of the training effect, while not beingtoo time-consuming.

Material such as Dantale 1 does not require training as each word list consistsof 25 words taken from a 200-word pool. They are therefore not repeatedeach time as with the Dantale 2 material.

A Dantale 2 training session should be conducted before the actual Dantale2 measurements begin. It is especially important for the very first set ofDantale 2 measurements as this is where the largest training effect is gained.Test subjects should be retrained for each room situation, due to both thetime interval between the Dantale 2 measurements and the fact that Dantale1 material is also presented between the two Dantale 2 measurements. Thesetwo factors could cause the test subjects to forget their Dantale 2 training.

A.3.5 Presentation Order

The order in which to present the speech material is not unimportant. Whenconducting psychoacoustic measurements it is usual to present the materialin either a random or weighed fashion to avoid any sequential errors. How-


ever, since this is a comparison of speech intelligibility measurements it isimportant that the same presentation sequence is used for both the real roommeasurements and the simulated room measurements. It is therefore accept-able to use a sequential order as long as the same sequential order is usedconsistently throughout the experiment.

Generally random order would not be appropriate as it is not possible to com-pare measurements optimally if they are derived from different sequences.

A weighed order could be adequate as long as the same sequence is usedthroughout the experiment. There may, however, be issues regarding theSNR sequence since it would be inappropriate to present the speech mate-rial with the lowest SNR first as this could confuse and frustrate the testsubjects.

A sequential order would probably be best for this type of experiment. Thislessens the complexity of creating the measurements and also assists withthe familiarization of the measurement procedure. It also makes the pro-cedure homogeneous for all test subjects and is therefore better suited forcomparison.

For this project there are five areas where the choice of sequence can poten-tially influence the measurements:

• Room order.

• Real-room/simulated-room order.

• Speech material type order.

• Receiver position order.

• SNR presentation order.

Using the same room order for all test subjects could create order effects.However, since the measurement segments for each room are rather large,it seems unlikely that one room will have a large impact on the next room.There might be a short initial training period involving changing rooms be-fore the test subjects become acquainted with the sound of that perticularroom, but this should not last long and would most likely be compensatedfor during the first measurement.

Whether to start with a simulated room or real room is not very importantas long as the order is continued through out the measurements. As withthe room order, the real room/simulated room order may also have a slight


effect when changing from one to the other, but this should quickly lessen.

The order of the speech material can potentially influence the intelligibilityif not presented uniformly. It would be unnatural to constantly alternatebetween Dantale 1 and Dantale 2 speech material, as this would confuse thetest subjects and also be very difficult to administer. Therefore, each speechmaterial should be presented separately. Whether the Dantale 1 or Dantale2 material is presented first should not directly influence the measurements,as they are two completely separate speech materials. However, one couldhypothesize that the test subject may become so used to the Dantale 2 ma-terial, that switching to Dantale 1 may be more confusing than switchingfrom Dantale 1 to Dantale 2.

As with the speech material, the receiver positions should not be alternateduntil a full set of measurements for one position is taken and it would there-fore be natural to change positions. There could be a potential sequentialeffect between the first and second position, if the test subject has not fullyunderstood the measurement process in the first position. This could mainlyoccur for the Dantale 2 material, where training has a great effect on theresults.

The SNR order could possibly have the greatest order effect as the diffi-culty of each SNR influences the subsequent values. If presented in a ran-dom or weighted fashion, the resulting order effect would be random orweighted. This is not good for comparision purposes, even if the same ran-dom or weighted order is used for the comparison measurements, as it can bemore difficult to compare with all the other measurements. The sequentialorder is recommended for the SNRs. When presenting the speech materialthe SNR sequence should be descending rather then ascending so it becomesharder rather than easier. This creates a measurement environment, wherethe test subject is more aware of what to do and listen for. This shouldalso create a better Dantale 2 training, which is crucial for the first set ofmeasurements.

A.3.6 Setup method

The setup used for the real room and simulated rooms should be createdso the measurements taken from both are comparable. Seeing as these arespeech intelligibility measurements, it would be natural to create a normallistening situation such as a teacher or lecturer speaking to the class.

The measurement setup should be as reproducable as possible, as the ex-periments will be carried out over a long period of time. In the case of thereal room measurements, the setup has to be dismantled and reassembled


for each test subject for each real room. The simulated room measurementsare not dependent on a large setup as they are done in a listening boothwhere all the equipment is already located and where it does not have to beconstantly dismantled and reassembled.

For the real rooms, using an adjustable stand and a loudspeaker one cancreate a speech source of a desired height. To make the noise source andspeech source play from the same point two speakers can be combined, oneplaced on top of the other. To minimize the difference the top speaker can beplaced upside down so the tweeters are closer to each other. This, of course,means that the woofers are further apart, but the noise and speech presenteddo not contain much low frequency so it is the tweeter, which in fact createsthe majority of the sound, and especially its high frequency cues. Placingthe speakers on top of each other will normally ensure that there is the samedistance between both the woofers and tweeters, but this will then increasethe difference between the tweeters.

To ensure equal loudness from both speakers, so as to eliminate SNR dis-crepancies when presenting the material, each loudspeaker is calibrated toemit the same SPL. This is to ensure that the SNR inherent for the twoloudspeakers is as close to 0 dB as possible, so the speech intelligibility ma-terial SNRs are unaffected. This can be done using varible attenuators foreach loudspeaker. The presented sound should be the equivalent of a raisedspeech level, in order to better simulate a normal human speaker. The levelshould therefore be about 70 dB.

The loudspeakers’ calibrated SPLs should correspond to both the noise andspeech material SPLs to ensure that the correct presentation level is used.To do this the loudspeakers can be calibrated with Dantale 1 noise relativeto 0 dB SNR. The position with which to calibrate the loudspeakers shouldbe uniform for both rooms. Thus rather than calibrating from a receiverposition the loudspeakers should be calibrated at a distance of 1 m perpen-dicular from the source.

Since the material is presented in a uniform and sequential order there isno reason to use a computer to conduct the real-room measurements. Thematerial can be played from a CD player.

The material for the simulated measurements is also played from a CD, butfrom a computer rather then a CD player, since the listening booth alreadycontains a computer. This creates the same procedure for both the real-roomand the simulated-room measurements. The material is presented throughheadphones. There are several headphones to choose from such as SennheiserHDA 200, Telephonics TDH-39 and Sennheiser HD580 headphones. Since


there are going to be numerous measurements in the listening booth theSennheiser HD580 is the best choice, as they are the most comfortable head-phones to wear for a longer period of time.

There is no reason to calibrate the individual level of each source point asthese are purely electrical signals and the auralisations have been created us-ing Sennheiser HD580 headphone compensation. Also, unlike the real-roommeasurements, the auralisations have already mixed the speech and noisesignals, so each headphone speaker presents both speech and noise with theproper SNR.

The presentation level for the auralised material should match that of thereal room material. This means that they too should be calibrated to 70dB. To calibrate the headphones a similar point 1 m perpendicular fromthe speech source is used to auralise Dantale 1 noise as with the real room.ODEON, however, creates binaural auralisations using HRTFs rather thanmonaural auralizations so the levels are not directly comparable to the levelsmeasured in the real rooms using the SPL meter. This is not a very bigissue, however, as it is not crucial that the presentation levels are exactlythe same, since it is mainly the SNR that is the important factor.

The right ear of the headphones is calibrated using an artifical ear play-ing Dantale 1 noise relative to 0 dB SNR that has been auralized throughODEON 1 m from the source. To ensure that the levels are adequate theoperator listens to the level to see whether they are similar to those of thereal room measurements.

A.3.7 Environmental conditions

Environmental conditions should also be taken into consideration. If thereal room speech intelligibility measurements are to take place in the actualroom, then factors such as lighting, environmental noise, humidity or outsidedistractions may have an effect on the results. Most of these conditions arenot easy to control so there is a randomness to the real-room measurements.

If the real room measurements are conducted in the same listening booth asthe simulated room measurements then there is a better comparison. Thisis because the same exact sound is used for all test subjects, which is playedunder a controlled environment.

A.4 ODEON Parameters

There are some issues regarding ODEON and its ability to create realisticauralizations for the modelled rooms.


A.4.1 Model accuracy/details

The level of detail in the model used may be an issue. If the models used torepresent the real rooms are too simplistic the resulting auralizations maybe flawed. The geometrical details in the room may have an influence onthis, although there is, of course, a point at which higher levels of detail willnot change the outcome.

There are also many details in the ODEON model that can have an effect onthe outcome. The choice of materials used for the model may also be overlyapproximated or simply incorrect. Many small parameters regarding thematerials used in the ODEON models, such as the scattering coefficient forthe surfaces or damping coefficients may have an influence on the outcome.These issues are very relevent if the ODEON models are to be built fromscratch. This is especially true for people new to ODEON, as experience isneeded to create an accurate model.

The models used for this project are supplied by DTU and they have beenmade by professional ODEON users.

Classroom 019/352 seems to be adequately modelled and has a fairly highlevel of detail. The real door has been changed to a glass door, so the mate-rial used in ODEON for the door has also been changed to glass.

Auditorium 021/341 may, however, be over-simplified. The seating areais approximated by a single surface. This could create an incorrect pointresponse for the receiver positions situated above them, as the real seatingarea contains surfaces slanted in the opposite direction.

A.4.2 Auralization Setup

The setup used by the ODEON program is very important for the outcomeof the auralizations and their corresponding intelligibility results.

The number of rays used to generate the point response for each receiverposition can be chosen. ODEON suggests a recommended number of rays.Since the number of rays defines the point responses, it is not wise to choosea fewer rays than the recommended. It may be a good idea to create theauralizations using more rays, maybe twice as many to ensure that the pointresponses are adequate.

It is also recommended that the auralizations compensate for the headphonesused for presenting the material in the listening booth. This should give abetter, more immersive auralization and therefore be closer to the actual


sound of the real room.

A.4.3 Auralization level calibration

To create the same measurements for both the real room and the simulatedroom, the auralized material should be presented at the same level as withthe real room measurements. In the real room measurements the loudspeak-ers are calibrated to 70 dB using an SPL meter at a distance of 1 m fromthe loudspeakers’ tweeters, so that the loudspeakers produce an SNR of 0.

The same setup should also be done for the simulated rooms. However, theauralizations are not as easy to measure. This is due to the binaural record-ings used by ODEON, which use HRTFs. This means that the auralizedsound is recorded at both ears, rather than at a single receiver point. TheHRTF adds to the distance of the intended receiver points and also gives aunique sound with directionality for each ear. Measuring the auralizationwith an artificial ear and a SPL meter would therefore not be comparableto measuring the output of each loudspeaker at a distance of 1 m. Since thesound is different for each ear the calibration would also depend on whichear was used for the level adjustments.

This, of course, only influences the presentation level and does not affect theSNR and is not perceived as a problem for the integrity of the project. Theauralized sound can still be subjectively adjusted to a level similar as thatused in the real rooms.

B PROJECT PILOT TEST - SPEECH INTELLIGIBILITY MEASUREMENTS 76

B Project Pilot Test - Speech Intelligibility Mea-surements

A small pilot test project was created to test the full measurement procedure,along with all the parameters that contribute to it. By carrying out a pilottest of the entire experiment it is possible to identify and rectify problemareas before the majority of the measurements have taken place.

This pilot test describes all the aspects of the measurements along with theprocedure, the setup and the results. A conclusion on the pilot test experi-ment was then made after the results were assessed. Any adjustments werethen made to the procedure and/or parameters and retests were carried out.

The most interesting aspect of the pilot test measurements is to verify thatthe intelligibility measured from the test subjects is within the range from0% to 100%. If the measured intelligibility is out side this range, then anadjustment needs to be made to the discrete SNR values.

Another interesting thing worth examining is whether the training tracksfor the Dantale 2 material provide an adequate enough training for the ac-tual Dantale 2 measurements. This goal of the training tracks is to give notonly sentence training but also difficulty training, so it is important thatthe training tracks are not too difficult as low intelligibility scores would notadequately train the test subjects.

B.1 Test subjects

The test subjects used for this pilot test were recruited from the DTU campusarea by using flyers. See Appendix H on page 111 for a detailed descriptionof the flyer that was used. The flyers indicate that test subjects are paid fortheir participation.

Two of the eligibility requirements for test subjects are that Danish is theirnative language and that they have normal hearing.

Each potential test subject has their hearing tested and an audiogram is pro-duced. The audiogram is conducted using an Interacoustics Audio TravellerAA222 audiometer, which fulfills the IEC 60645 standard.[IEC 60645, 2001]The audiometer uses Sennheiser HDA200 headphones, which are calibratedin accordance to reference values found in ISO 389-8.[ISO 389-8, 2005] Theaudiogram is conduced automatically using an ascending method in accor-dence to the suggested ISO 8253-1 standard.[ISO 8253-1, 1989] Subjects arerejected if any points exceed 15 dB HL.


A questionnaire was also given to the test subjects. It was compiled in accor-dance with ISO 389-9.[ISO 389-9, 2007] The answers from the questionnaireare evaluated by the operator. If the operator deems that the test subjectis not eligible for the experiment, the test subject is then dismissed. SeeAppendix I, page 112, for a detailed description of the questionnaire givento the test subjects.

B.2 Measurement Material

The material used for the experiment was both Dantale 1 and Dantale 2speech and noise material presented at six different discrete SNR values fortwo different positions. This was done for two different rooms for both thereal room and simulated room measurements.

Six different discrete SNR values were chosen for the Dantale 1 material andsix different discrete SNR values were also chosen for the Dantale 2 material.

In order to present the material four CDs were created, one for each realroom and simulated room measurement situation. Each CD contains Dan-tale 1 and Dantale 2 material with the appropriate SNRs required for theexperiment. Each CD contains 25 tracks of Dantale material and is createdto be played in sequential order.

On each CD the order in which the material is presented is the same:

• Tracks 1 to 6 contain Dantale 1 Material for Position 1, descendingfrom highest SNR to lowest SNR.


• Track 13 contains Dantale 2 Material created for Position 1, with ran-dom SNR values for each sentence.



At the end of each track there is a 10-second pause indicating the end of thetrack.

There are 10-second pauses after each sentence for the Dantale 2 material,which is when the test subject has to repeat the material.


There is about 58 minutes of Dantale material on each CD. The Dantale1 material fills about 25 minutes and the Dantale 2 material fills about 33minutes.

Each CD also has a track 26, which contains 20 seconds of silence and atrack 27, which contains a Dantale 1 noise calibration signal relative to 0dB to be used for adjusting the loudspeakers and the headphones during themeasurement setup.

B.3 Measurement Setup

The intelligibility is measured in two separate ways depending on whether itis simulated room measurements or real room measurements.

B.3.1 Simulated Rooms

Due to the nature of the ODEON-simulated speech intelligibility material,the material is best presented under a controlled environment where the au-ralised headphone compensations have been taken into consideration. To dothis seveal listening booths in DTU were used.

A computer in the listening booth is used to play the speech intelligibilitymaterial, which is located on four CDs. The material used is presented tothe test subjects through Sennheiser HD580 headphones during the mea-surements.

The headphone calibrations were made using a B&K 4153 artificial ear[IEC 60318-1, 1998] with circumaural headphone adapter [IEC 60318-2, 1998]and a B&K 2636 SPL meter. Dantale 1 noise is used to calibrate the head-phones so that the output level is 70 dB relative to an SNR of 0 dB. This isdone using a pure Dantale 1 noise signal, which is equivalent to those usedin the measurements just 1 m from the source. The signal is played throughthe right ear of the headphones and the SPL level is observed. The left earmust be silent or the measured SPL will be incorrect.

The computer in the listening booth has a digital software attenuator thatcan lower the level of the output. An appropriate attenuation is found thatgenerates a 70 dB SPL over a long integration time. This is done for eachODEON-simulated room and the attenuation found is noted for future ref-erence.

There are several listening booths that can be used and each of them need tobe calibrated in order to generate the correct output level. The listing boothsused were the CAHR left listening booth and the big listening booth. The


attenuations required to deliver a 70 dB SPL relative to 0 dB SNR Dantale1 noise signal can be seen in table reftab:HeadphoneAttenuationLevels.

CAHR Left Booth Big BoothRoom 019/352 -5.81 dB -12.2 dB

Auditorium 021/341 -12.2 dB -18.4 dB

Table 17: Headphone Attenuation Levels

B.3.2 Real Rooms

To measure the intelligibility for the real rooms it is necessary to use a lotof equipment:

• 2 Dynaudio loudspeakers.

• 2 Amplifiers.

• 2 variable attenuators.

• A CD player.

• A speaker stand.

• A tripod with a SPL meter mount.

• A B&K Type 2240 sound pressure level meter.

• A large, solid flight case.

• 2 5 m long speaker cables.

• 2 BNC to phono cables.

• 2 BNC to BNC cables.

• A power splitter.

The general setup of the room can be seen in Figure 29. The loudspeakerneeds to be located in the same position used by the ODEON auralisations,see chapter 5.2.3, page 25, for a discription of the rooms’ layouts. The coor-dinates used for the loudspeakers can be seen in table 3, page 27. These arerelative to the middle of the rooms from blackboard for both rooms, see fig-ures 11 and 12,page 26, for a discription of the source and receiver positionsfor both rooms.


The flight case (H) is placed on its side in the correct location according tothe coordinates, and the speaker stand is placed on top of it. The speakers(A) are then placed on the speaker stand (E) pointing away from the black-board facing the seats. One speaker is placed on the stand and the secondspeaker is placed on top of the first turned upside down. The distances fromthe tweeter diaphragms to the blackboard should be 1 m.The left and right channel outputs from the CD player (D) are connected tothe two variable attenuators(B), which are then connected to two amplifiers(C) using the correct cables. The output from the amplifiers is then con-nected to the speakers.

Figure 29: Real room measurement setup

The speakers are calibrated individually by playing a Dantale 1 noise signalrelative to 0 dB SNR and measuring the SPL with a B&K type 2240 SPLmeter (G) at a distance of 1 m perpendicular to the source. The SPL meteris fastened to a tripod (F) and set at the same height as the tweeter. Thecalibration signal is located on the appropriate room CD on track 27. Along integration time is used on the SPL meter. Each speaker is calibratedby adjusting the variable attenuators so that they are as close to 70 dB aspossible with as little SPL difference as possible. The attenuators can beadjusted in 1 dB steps. Only one speaker may be turned on at a time forthe calibration. The measured SPLs for each speakers are noted.

After the speakers are calibrated the appropriate CD with the speech intel-ligibility material is loaded into the CD player and the measurements areready to begin.


B.4 Measurement Procedure

The measurements for each test subject were conducted over two 1-day pe-riods. Each day the speech intelligibility for one real room and its ODEON-simulated equivalent is measured. When the first day of measurements iscompleted, the results are reviewed and aby changes are made for the sec-ond half of the measurements as well as for any retests that may be necessary.If a retest is necessary the procedure incorporating the new changes will berepeated for a new test subject and a the results will then be evaluated.

The measurements start with the simulated room measurements first fol-lowed by the real room measurements.

B.4.1 Simulated Room Measurement Procedure

The appropriate simulated room CD is loaded into the computer and thefirst track is selected and made ready for the test subject. The test subjectis shown into the listening booth and takes a seat by the desk facing awayfrom the operator who sits behind the test subject. The test subject thenputs the B&K HD580 headphones on and the measurements can then begin.

The simulation measurements start by playing tracks 1 to 12, which con-tain Dantale 1 material. The test subject is told to listen for single Danishwords that are masked by a constant noise and are instructed to write theunderstood material down on a supplied Dantale 1 response sheet, see Ap-pendix L, page 116. The test subject is told that there are 12 tracks and isinstructed to write only the words that he hears or thinks he hears. He isalso instructed to switch to the next column when he hears a pause in thetrack and is informed that the noise level will increase during the experiment.

The test subject is told that these measurements will take about 25 minutesto complete. If there are any questions or if a break is need the test subjectindicates this to the operator who then pauses the CD.After the first 12 tracks have been played there is a short break.

After the break tracks 13 through 25 are played, which contains Dantale 2material. The test subject is told to listen for a meaningful 5-word Dan-ish sentence that is masked by noise and that after the sentence there is a10-second pause. The test subject is instructed to repeat as much of the sen-tence as possible during each 10-second pause. The operator then marks thecorrect words repeated by the test subject in the test subject intelligibilityscore sheet, see Appendix K, page 114.

The test subject is told that these measurements will take about 35 minutes


to complete. If there are any questions or if a break is need the test subjectindicates this to the operator who then pauses the CD.When the 25th track is finished the simulated room measurements are over.The test subject is then given a short break.

B.4.2 Real Room Measurement Procedure

After the simulation measurements done the operator and test subject walkto another room where the equivalent real room measurements are to takeplace. There the setup for the real room measurements has already beendone beforehand as stated in Appendix B.3, page 78.

The appropriate real room CD is loaded into the CD player and the firsttrack is selected and made ready for the test subject. The test subject isshown into the room and is seated in position 1 while the operator sits nextto the CD player near the source. The test subject is told that the sametype of measurements as those carried out in the listening booth are goingto take place.

The real room measurements start by playing tracks 1 to 12 which containDantale 1 material. The test subject is told to listen for single Danish wordsthat are masked by a constant noise and are instructed to write the un-derstood material down on a supplied Dantale 1 response sheet. The testsubject is told that there are 12 tracks and is instructed to only write downthe words that he hears or thinks he hears. He is also instructed to switchto the next column when they hear a pause in the track and that the noiselevel will increase during the experiment.

The test subject is told that these measurements will take about 25 minutesto complete. If there are any questions or if a break is need the test subjectindicates this to the operator who then pauses the CD.

After tracks 1 through 6 have been played, the operator then stops the CDand instructs the test subject to sit in position 2. The operator then playstracks 7 through 12. After the 12’th track has been played there is a shortbreak

After the break the test subject is instructed to sit in position 1 and tracks13 through 25 are played. These contain Dantale 2 material. The test sub-ject is told to listen for a meaningful 5-word Danish sentence that is maskedby noise and that after the sentence there is a 10-second pause. The testsubject is instructed to repeat as much of the sentence as possible duringeach 10 second pause. The operator then marks the correct words repeatedby the test subject in the test subject intelligibility score sheet.


The test subject is told that these measurements will take about 35 minutesto complete. If there are any questions or if a break is need the test subjectindicates this to the operator who then pauses the CD.

After tracks 13 through 19 have been played, the operator then stops theCD and in instructs the test subject to sit in position 2. The operatorthen plays tracks 20 through 25. When the 25’th track ends the real roommeasurements are completed.

B.5 Pilot Test 1 - Auditorium 021/341

Two test subjects were used in the pilot test, both were females and were 21and 25 years old. They fulfilled the requirements needed for this project asstated in Appendix B.1, page 76.

On the first day both test subjects’ intelligibility were measured for audito-rium 021/341, both real and simulated. The measurement procedure used isthe same as stated in Appendix B.4, page 81.

The six discrete SNR values used for the Dantale 1 and Dantale 2 materialare +3, 0, -3, -6, -9 and -12 dB and 0, -2, -4, -6, -8 and -10 dB respectivelyas explained in Appendix A.2.5, page 65.

Track 13, the training track used for the CD’s, uses the same Dantale 2 SNRvalues but in a random order. The first two sentences on the training trackdo not use the SNR values -8 and -10 dB.

The measurements start with the ODEON-simulated auralizations, whichare presented in a listening booth situated in DTU building 355. CD 4containing the auralized Dantale 1 and Dantale 2 material for auditorium021/341 is played. The simulated room measurements take about 75 minutesto complete.

After the simulated room measurements the operator and test subject walkto auditorium 021/341 and begin the real room measurements. CD 2 con-taining the Dantale 1 and Dantale 2 material for auditorium 021/341 isplayed. The real room measurements take about 75 minutes to complete.

When the measurements are completed the operator then scores the writtenDantale 1 material as well as the repeated Dantale 2 material for auditorium021/341. The resulting intelligibility scores for both test subjects are thencalculated, compared and assessed.


B.5.1 Auditorium 021/341 Results

After scoring the reproduced speech material derived from the test subjectsfor auditorium 021/341 the total intelligibility results are created and thencompared to see if there are any issues that need to be addressed.

The intelligibility results can be seen in figures 30 and 31. The results areshown for both test subjects for the real and simulated simulations.The results show that all the measured intelligibility scores are within therange from 0-100% without having multiple 0% or 100% points in sequence.

Figure 30: Pilot test 1, Dantale 1 speech intelligibility results for auditorium021/341.

The results for the Dantale 1 material show that there is a large differencebetween the simulated and real room measurements when situated in posi-tion 1, where the real room measurements produce much higher intelligibilityresults. The differences range from 10% to 40%. This difference is howevernot apparent when measured in position 2, except for one SNR value, therethe real room and simulated room intelligibility results are very close to-gether.

The same trend is apparent when measuring with the Dantale 2 material.When measured in position 1 there is the same large difference in intelligi-bility as with the Dantale 1 material. The difference is more constant andis about 30% to 40%. For a 0 dB SNR there is less than 50% intelligibil-ity which is the same as the -2 dB SNR. The 0 dB should have generatedhigher results, so this could indicate that the training track was not adequate.

The difference in intelligibility for position 2 is not as great. Here the simu-lated room results are about 10% lower than the real room results.



The training track for the simulated auditorium 021/341 does not adequatelytrain the test subjects. The test subjects understood only a very smallnumber of words in the training track. They understood 18 and 22 wordsrespectively out of 150. This can be seen in table 18 on page 95. Theintelligibility is expected to be low for SNR values -8 and -10 dB but thereshould be higher intelligibility for SNR values 0, -2, -4, and -6 dB, with moresentences being completely understood.

B.5.2 Discussion and Conclusions

The intelligibility results for auditorium 021/341 show that the chosen dis-crete SNR values are reasonable as they are rather evenly distributed through-out the 0% or 100% intelligibility point range. For the Dantale 1 material theintelligibility ranges from 4% to 88% while the Dantale 2 material range from0% to 96%. A general psychometric curve is also apparent, which is expected.

There is, however, a rather alarming difference in intelligibility when com-paring the real room results with the simulated room results for both Dantale1 and Dantale 2 in position 1.

The Dantale 2 training track used for for the simulated measurements is notadequate. When examining the individual sentences, intelligibility resultsfrom the training track show that the intelligibility is way too low and thatthe training should be made much easier, to ensure a greater training effect.This lack of training could account for the large difference in intelligibilityfor the Dantale 2 measurements in position 1, but the fact that the Dantale1 results produce almost the same difference as the Dantale 2 results do,


indicates that the difference is not entirely due to a lack of training.

The training track for the ODEON-simulated Dantale 2 material for the au-ditorium was made easier by increasing the SNR for all the sentences by 2dB. This was done for room 019/352 in anticipation of similar difficultieswith the training track.

The test subjects needed the Dantale 2 material for the simulated audito-rium 021/341 to be retested. This was carried out after the simulated roommeasurements for room 019/352.

B.6 Pilot Test 1 - Classroom 019/352 and Retest

On the second day both the test subjects’ intelligibility were measured forclassroom 019/352, both real and simulated. The same measurement proce-dure as with the auditorium measurements was used.

The SNR values for track 13, the training track used for the CD’s, was raisedby 2 dB from the original Dantale 2 SNR values and were still presented ina random order. This means that the SNRs used for the training track were+2, 0, -2, -4, -6 and -8 dB. The first 2 sentences in the training track did notuse the SNR values -6 and -8 dB.

The measurements started with the ODEON-simulated auralizations, whichwere presented in a listening booth situated in DTU building 355. CD 3 con-taining the auralised Dantale 1 and Dantale 2 material for classroom 019/352was played.

After the simulated room measurements for room 019/352 were completedthe test subject was given a short break. After the break a retest of theDantale 2 material for position 1, tracks 14 to 19, for the simulated audito-rium 021/341 was conduced. There was no additional training as this wasnot necessary due to all the previous Dantale 2 material just presented. Thesimulated room measurements including the retest took about 105 minutesto complete.

After the simulated room measurements the operator and test subject movedto room 019/352 and began the real room measurements. CD 1 containingthe Dantale 1 and Dantale 2 material for classroom 019/352 was played. Thereal room measurements took about 75 minutes to complete.

When the measurements were completed the operator scored the writtenDantale 1 material as well as the repeated Dantale 2 material for classroom019/352. The resulting intelligibility scores for both test subjects were then


calculated, compared and assessed.

B.6.1 Classroom 019/352 Results

After scoring the reproduced speech material derived from the test subjectsfor classroom 019/352 the total intelligibility results were created and thencompared to see whether there were any issues that needed to be addressed.

The intelligibility results can be seen in figures 32 and 33. The results areshown for both test subjects for the real and simulated measurements.The results show that all the measured intelligibility scores are within therange from 0-100% without having multiple 0% or 100% points in sequence.

Figure 32: Pilot test 1, Dantale 1 speech intelligibility results for classroom019/352.

The results for the Dantale 1 material show that there is a large differencein intelligibility for four points between the simulated and real room mea-surements when situated in position 1, where the real room measurementsproduce much higher intelligibility results. There are however, two pointsthat differ very little.

For position 2 there is not much difference in intelligibility at all. Therethe real room and simulated room intelligibility results are very close toeach other, and both real and simulated results alternate between havingthe greatest intelligibility.

The Dantale 2 results for position 1 follow the same trend as the Dantale1 material which generally shows a large difference in intelligibility rangingup to 50%, however, there are a few points that are similar. There is alsoa slight difference in intelligibility for position 2 where the simulated room



results seem to be almost constantly 10% lower than the real room results.

The training track for room 019/352 is more reasonable than that takenfrom auditorium 021/341. There is a good agreement between the intelligi-bility and SNR values as the higher SNR values +2, 0 and -2 produce highintelligibility. This can be seen in table 19, page 96.

B.6.2 Auditorium 021/341 Retest Results

The Dantale 2 intelligibility results for the simulated auditorium 021/341for position 1 can be seen in figure 34. Here it is apparent that the trainingreceived was not adequate. The intelligibility increases for the SNR values-6, -4, -2 and 0 dB with a maximum gain of about 25%.

B.6.3 Discussion and Conclusions

The intelligibility results for classroom 019/352 show that the chosen dis-crete SNR values for the Dantale 1 material are reasonable as they resultin intelligibility scores distributed from 16% to 96%. For the Dantatle 2material intelligibility scores are distributed from 4% to 100%. The generaloutline of a psychometric curve is apparent for both materials.

The discrete SNR values chosen for both classroom 019/352 and auditorium021/341 have resulted in intelligibility results that range between 0-100%without having redundant SNR values that produce multiple points of ei-ther 0% or 100%. This means that the discrete SNR values chosen for boththe Dantale 1 and Dantale 2 material can confidently be used for the remain-der of the experiments. The fact that the SNR values produce intelligibility


Figure 34: Pilot test 1, Dantale 2 speech intelligibility retest results for auditorium021/341.

results that only once reach the 0% and 100% points show that there is roomfor subjective fluctuations without the measurements being either too easyor too hard.

The training track is rather crucial for the results of the simulated Dantale 2material in position 1 and can result in a 25% intelligibility increase as withauditorium 021/341. The changes made to SNR values in the training trackshould only influence the Dantale 2 material presented to the test subjectfor the first position as that position will in itself train the test subject forthe following positions for both simulated and real rooms.

The results from the training track should therefore be examined in a newpilot test to determine whether the training difficulty should be changed.

The intelligibility results obtained from this pilot test were used for the finalresults, where the retest data rather than the original data was used.

B.7 Pilot Test 2 - Auditorium 021/341 and Classroom 019/352

One 21 year old male test subject was used in the pilot test. The test subjectfulfilled the requirements needed for this project.

The six discrete SNR values used for the Dantale 1 and Dantale 2 materialare +3, 0, -3, -6, -9 and -12 dB and 0, -2, -4, -6, -8 and -10 dB respectively.Track 13, the training track used for the CD’s, uses the SNR values +2, 0,


-2, -4, -6 and -8 dB but in a random order. The first 2 sentences in thetraining track do not use the SNR values -6 and -8 dB.

On the first day the test subject’s intelligibility was measured for auditorium021/341, both real and simulated. The measurement procedure used is thesame as stated in Appendix B.4, page 81.

The measurements start with the ODEON-simulated auralizations, whichare presented in a listening booth situated in DTU building 355. CD 4containing the auralized Dantale 1 and Dantale 2 material for auditorium021/341 was played. The simulated room measurements took about 75 min-utes to complete.

After the simulated room measurements the operator and test subject movedto auditorium 021/341 and begin the real room measurements. CD 2 con-taining the Dantale 1 and Dantale 2 material for auditorium 021/421 wasplayed. The real room measurements took about 75 minutes to complete.This concludes the measurements for the first day.

On the second day the test subject’s intelligibility was measured for class-room 019/352, both real and simulated. The measurement procedure is thesame as that used for auditorium 021/341.

The measurements start with the ODEON simulated auralisations, which arepresented in a listening booth situated in DTU building 355. CD 3 contain-ing the auralized Dantale 1 and Dantale 2 material for classroom 019/352 asplayed. The simulated room measurements took about 75 minutes to com-plete.

After the simulated room measurements the operator and test subject movedto auditorium 021/341 and began the real room measurements. CD 1 con-taining the Dantale 1 and Dantale 2 material for classroom 019/352 wasplayed. The real room measurements take about 75 minutes to complete.

When all the measurements were complete the operator scored the writtenDantale 1 material as well as the repeated Dantale 2 material for both au-ditorium 021/341 and classroom 019/352. The resulting intelligibility scoresfor the test subject were then calculated, compared and assessed.

B.7.1 Classroom 019/352 and Auditorium 021/341 Results

After scoring the reproduced speech material derived from the test subjectfor classroom 019/352 and auditorium 021/341 the total intelligibility resultsare created and then compared to see if there are any issues that need to be


addressed.

The pilot test 2 intelligibility results for the auditorium can be seen in figures35 and 36 for Dantale 1 and 2 respectively.

The results for the auditorium show that all the measured intelligibilityscores are within the range from 0-100% without having multiple 0% or100% points in sequence.


The Dantale 1 results for the auditorium show that there is a large differ-ence for four SNR values between the simulated and real room measurementswhen situated in position 1, where the real room measurements producemuch higher intelligibility results. However, two points differ very little.

The results for position 2 fluctuate more, as there are three SNR values thatgenerate similar intelligibility results and three SNR values where there is a14-20% difference with the real room results being the highest.

The Dantale 2 results for the auditorium show that there is a large differ-ence in intelligibility between the real room measurements and the simulatedroom measurements for position 1 where the real room generates the highestintelligibility. The difference in intelligibility ranges from around 25% to 50%.

The results for position 2 are more similar than those produced in position1. The real room results fluctuate around the simulated results, changingfrom highest to lowest intelligibility several times for different SNR values.



The intelligibility results for the classroom can be seen in figures 37 and 38for Dantale 1 and 2 respectively.The results for the classroom show that the measured intelligibility scoresfor the simulated classroom is rather well distributed in the range from 0%to 100% without having multiple 0% or 100% points in sequence. This isnot the case for the real classroom results, which have multiple 100% pointsin sequence for the Dantale 2 material.


The Dantale 1 results show that there is a large difference in intelligibilityfor position 1 for five SNR values where the difference is about 25% to 45%.For an SNR of 3 dB the results become saturated around the 100% point.


The difference for position 2 becomes constant where the general simulatedroom results are about 10% lower than the real room results.


The Dantale 2 results for position 1 show that there are large intelligibilitydifferences for the three lowest SNR values but the difference seems to de-crease for the highest SNR values when approaching the 100% point.

The difference in intelligibility becomes much less in position 2 where fourSNR values produce results that are within 10% of each other. The remain-ing two SNR values generate results that very by about 20%.

B.7.2 Discussion and Conclusion

The test subject results from pilot test 2 were generally higher then thosegenerated by the test subjects in pilot test 1. This is most likely becausethe test subject may simply be better at understanding the speech materialthan the other subjects.

The SNR values chosen are generally very good as they produce a wide rangeof intelligibility scores. The test subject produced very high intelligibility re-sults for the real classroom measurements. However, the SNR values shouldnot be changed as the corresponding simulated classroom intelligibility re-sults are still lower than the real classrooms. Also the fact that the two othertest subjects produced lower intelligibility results show that there can be awide variety of results for each SNR value.

The training track results were adequate, but this test subject was also


clearly better at understanding the material than the previous two test sub-jects. The training track may still be inadequate for some test subjects.Therefore the training track for the simulated Dantale 2 material should bemade easier to accommodate all test subjects, as it is better to be too easythan too hard. This is done by increasing the SNR for all the sentences byan additional 2 dB to 4 dB over that of the regular Dantale 2 material SNR.

Also the training track auralisation should be changed to simulate position2 instead of position 1 as the results indicate that the intelligibility is higherin position 2.

There is no need to carry out any further pilot tests. The SNRs chosenare suitable and the training track used has been made considerably easiercompared to the first iteration.

The intelligibility results obtained from this pilot test were used for the finalresults.

C PROJECT PILOT TEST RESULTS 95

C Project Pilot Test Results

C.1 Pilot 1 - Training Results

Simulated Auditorium 021/341 SNR (dB) Subject 1 Subject 2Sentence 1 -2 0 0Sentence 2 -6 0 0Sentence 3 -6 1 0Sentence 4 -4 1 1Sentence 5 -6 0 1Sentence 6 -10 0 0Sentence 7 -4 1 0Sentence 8 -4 0 0Sentence 9 -2 1 0Sentence 10 -4 0 0Sentence 11 -2 0 3Sentence 12 -4 1 0Sentence 13 -6 0 2Sentence 14 -8 0 0Sentence 15 -2 0 0Sentence 16 0 1 3Sentence 17 -4 1 2Sentence 18 -4 1 0Sentence 19 0 3 5Sentence 20 -6 2 1Sentence 21 -8 0 0Sentence 22 -2 2 1Sentence 23 -2 2 2Sentence 24 -8 0 0Sentence 25 -8 1 0Sentence 26 -10 0 0Sentence 27 -4 0 0Sentence 28 -10 0 0Sentence 29 -4 0 0Sentence 30 -8 0 1

Table 18: Pilot test 1 simulated auditorium 021/341 training track results.


Simulated Room 019/352 SNR (dB) Subject 1 Subject 2Sentence 1 0 5 5Sentence 2 -4 1 0Sentence 3 -8 0 0Sentence 4 -10 1 0Sentence 5 -2 3 3Sentence 6 -2 5 5Sentence 7 -10 0 0Sentence 8 -2 4 3Sentence 9 -8 1 0Sentence 10 -10 0 0Sentence 11 -2 0 4Sentence 12 -2 2 3Sentence 13 0 5 5Sentence 14 0 4 4Sentence 15 -6 1 1Sentence 16 -2 2 3Sentence 17 -10 0 0Sentence 18 -2 5 4Sentence 19 -2 0 4Sentence 20 -10 0 0Sentence 21 -4 2 3Sentence 22 -4 4 2Sentence 23 -2 4 5Sentence 24 -4 0 1Sentence 25 -4 3 1Sentence 26 -6 0 3Sentence 27 0 4 5Sentence 28 0 4 5Sentence 29 -4 3 4Sentence 30 -10 0 2

Table 19: Pilot test 1 simulated room 019/352 training track results.


C.2 Pilot 2 - Training Results

Simulated Auditorium 021/341 SNR (dB) Subject 1Sentence 1 0 0Sentence 2 -4 1Sentence 3 -4 1Sentence 4 -2 3Sentence 5 -4 0Sentence 6 -8 0Sentence 7 -2 1Sentence 8 -2 0Sentence 9 0 1Sentence 10 -2 2Sentence 11 0 0Sentence 12 -2 2Sentence 13 -4 2Sentence 14 -6 2Sentence 15 0 2Sentence 16 2 4Sentence 17 -2 4Sentence 18 -2 4Sentence 19 2 5Sentence 20 -4 0Sentence 21 -6 2Sentence 22 0 4Sentence 23 0 3Sentence 24 -6 0Sentence 25 -6 1Sentence 26 -8 0Sentence 27 -2 2Sentence 28 -8 0Sentence 29 -2 4Sentence 30 -6 0

Table 20: Pilot test 2 simulated auditorium 021/341 training track results.


Simulated Room 019/352 SNR (dB) Subject 1Sentence 1 2 5Sentence 2 -2 2Sentence 3 -6 1Sentence 4 -8 1Sentence 5 0 3Sentence 6 0 5Sentence 7 -8 0Sentence 8 0 4Sentence 9 -6 1Sentence 10 -8 0Sentence 11 0 3Sentence 12 0 2Sentence 13 2 5Sentence 14 2 5Sentence 15 -4 0Sentence 16 0 2Sentence 17 -8 0Sentence 18 0 4Sentence 19 0 5Sentence 20 -8 2Sentence 21 -2 3Sentence 22 -2 4Sentence 23 0 3Sentence 24 -2 4Sentence 25 -2 4Sentence 26 -4 0Sentence 27 2 4Sentence 28 2 5Sentence 29 -2 3Sentence 30 -8 0

Table 21: Pilot test 2 simulated room 019/352 training track results.

D ODEON STI MAPPING 99

D ODEON STI Mapping

The STI has been mapped for both classroom 019/352 and auditorium021/341 for both the speech and the noise source. The results are for aheight of 1.2 m above the ground.

D.1 Classroom 019/352

Figure 39: ODEON calculated STI values based on the impulse response for class-room 019/352 using the speech source, mapped for the entire room.

Figure 40: ODEON calculated STI values based on the impulse response for class-room 019/352 using the noise source, mapped for the entire room.

D ODEON STI MAPPING 100

D.2 Auditorium 021/341

Figure 41: ODEON calculated STI values based on the impulse response for audi-torium 021/341 using the speech source, mapped for the entire room.

Figure 42: ODEON calculated STI values based on the impulse response for au-ditorium 021/341 using the noise source, mapped for the entire room.

E DANTALE 1 WORD LISTS 101

E Dantale 1 Word Lists

Dantale 1 Word lists 1-8List 1 List 2 List 3 List 4 List 5 List 6 List 7 List 8SALT SKOV VÆG VASK HEST PELS NÆB NÅLSPOR KRUS KLAT HUND LAND NYT KNÆ GÆSTHALM SOL SOK TRÆT SØ ENG SMÅ SØDGÅS HVID SNE BY KROP KURS BUSK VINDMØRK VAGT HALS TAG PÆN HALM AND PRIKTELT HORN BORD SNOR BLÅ SØM KRIDT HATHÅR SPIL JAGT BRED HÆL GRÅ GRØN FLOTPIL RÅB SKUR HANK VINK VÅD SANG SORTFLOD KORT RIS JÆVN POST HÆK TOM FÅRSMAL SE DÆK FOD KO BANK DAL SKEBRØD GARN FISK GLAS KNAP KRUDT TÆT KALKKAT RENT HJEM NAVN NØD MUS BÆNK MANDTUNG MAD FLÅ FUGL TAND IS HÅND PASSTOK SKO MÅL DAMP BÅL KOST HØST HUSMEL BRUN KANT ARK SÆK KROG PORT KLUDMUND GÅ PRIS SKIB GRØD LUFT BIL BÆKBREV MÆLK DEL DØGN SMIL SAND PROP FESTSKIND STEN BÅD LOFT REGN DIGT SØVN BUSGÅRD DYB VOGN SAV NÅ ÆG KORN VÆGTBEN HJUL TØJ STOL DANS TAP KOP ILDGRÆS SENG SPAND MYG PIND SAKS NY DØRØL ARM SLÅ BØF KNOP VAND LÅS PÆLJORD FART LØN STOR LE DYR VEJ STÅGED SLOT VAT HAVN TRÅD GAS RIST SKUDNET SMØR HÅRD NAT TUR KLAP KÆLK REN

Table 22: Dantale 1 word lists 1-8


Dantale 1 Word lists 9-16List 1 List 2 List 3 List 4 List 5 List 6 List 7 List 8ENG STOK BØF MYG MÆLK PRIS NAVN BILBUSK TRÅD MUS ØL BRED SPOR SKE VANDFLÅ VAT MEL PROP DØGN MUND NÅL FLÅSKIB PRIS KORN SOL NAT SMÅ DAL PÆLHJEM HAVN HØST KLUD BÆNK GLAS FISK SNORTRÆT RÅB PAS DANS VIND HUS HØST SNESKUD HÆL STEN BORD IS STOR BUSK HÅRKOST SMIL SAKS GÆST ARM PROP SØD TAGHAT MAD HALM SØM REN BÅL TØJ POSTNØD STOL LUFT BEN SLOT DYR KROG LOFTNÅL SØ KROG KO SE LAND KLUD PÆNSNE GRÆS NØD GRØD BÅD SKIND VÆGT NÆBLAND STOR DÆK HORN KRUDT NYT SPAND PINDGRØD RENT SKIND FÅR KNÆ TUNG REN SOLPORT BÅD PÆN VÆGT SLÅ REGN BÆNK NØDMAND GRØN MÅL PORT STEN HJEM PIL MYGKO SMØR SØD BRUN VASK TRÆT JAGT KOPFLOT PIL JORD SØ NØD JORD VASK KÆLKKAT DAL PÆL PELS HAVN VINK KURS STORKLUD AND VAGT HÅND TUR TRÅD BY RISTTAG FOD KURS RIST VAND PORT NÅ GRØDFISK HJUL SKO SKE KOST LØN MAND SANGHVID DYR NÅL SOK KORN GRØN SE GASTUR KORT SPOR KNAP BRØD BORD GARN GRØNBEN DYB LE HUND BUS RÅB MEL GLAS



Dantale 1 Word lists 17-24List 1 List 2 List 3 List 4 List 5 List 6 List 7 List 8SAND RENT JORD BIL SKE SMØR GARN KROGHORN DANS JÆVN SØ PORT KÆLK IS BRUNSTOK BORD KURS TAND TAG KOP ARM DAMPREGN TAP BRØD HANK JORD MAND KANT DÆKVOGN DIGT BRUN PAS NAVN FART VAT SOLVEJ KLAP PÆL RÅB LOFT NÅL PIND SMALGÅ DØGN KAT RIST DÆK DANS LÅS DØGNSTOL SNOR GRØN TRÆT BÆK KNÆ MUS HUSSLÅ BEN NY DAMP SKO GRØD RIST SORTMÆLK BÆK VAGT DEL SØD KO MÆLK LØNRÅB HUS ARM BÅL SKUD DEL BRØD HÆLBANK FISK SKUR SNOR BEN SLOT TAG BUSKTOM BÅD SMAL BRED DIGT SØM SKUD KRUDTVÅD PIND NYT HAT VÅD AND JÆVN VINKSKIB ENG GAS PIL SØVN NAT HALM VANDBÆNK TUNG VAND RIS MUND HORN KORT SØSENG KRIDT TOM MUS HEST ENG PORT PILHØST KROG REGN SAKS MÅL GAS SPOR PRIKDEL NØD BUSK FOD SMAL TRÆT DIGT SKOVHÆK FUGL ØL BLÅ STOL NÆB BÆK NATBÅL MØRK KOST SLÅ REN VEJ HAT TAPKLUD HALS SÆK HÆK STÅ FEST TAND SÆKSKOV SANG SNE NØD BÅD VASK SNE RÅBKO VASK MÆLK PRIK PÆL SAKS BEN KOMAND SE BÆNK LE KLAT VÆGT HALS FLÅ



Dantale 1 Word lists 25-32List 1 List 2 List 3 List 4 List 5 List 6 List 7 List 8BØF GARN TAG NYT KOST HALM LØN KLUDSENG HALM MEL MUND PÆL NY DØGN SKINDFART VÆG ØL SOK HÆK TAND PRIK PRISKNOP DANS VASK NÆB KÆLK ARM DAL ILDFUGL KALK BÆK LØN GRÅ TØJ REN VOGNKOST RIS MØRK ILD KURS BRED TRÆT FARTSAKS ENG PRIK DÆK RENT KAT NET KRUDTKAT HÅRDT HJUL STOR FART REGN FÅR MELHUND SOL SKIND KLUD ENG BÆNK FLOD HUSVÅD ÆG REGN HVID BLÅ MUS HANK SLÅBREV HORN BÆNK SOL SØVN BØF PROP HESTGRÅ PAS BRUN RÅB BÆK VAT SØVN GÅRDHÆK KROG SMAL KALK BIL AND SÆK HALSHAVN POST NÅ VEJ SMIL KLAT BY BÅDHØST VINK ARK MYG HALS GRØD STÅ BREVSTOL DØGN GAS FUGL PIL DØR FOD KLAPGÅRD BUSK DYR FLOT HÅND STEN STOR FISKLÅS MÅL KLAP TELT HORN FLOT HÅR DØRGLAS JORD VÅD VAGT KLAP SENG NÆB SANDJAGT HJEM SAV GÅS BREV VÆGT SMIL KORNVIND STÅ BRED NAVN SLÅ SØD MYG BILPRIS SPIL STOK RIST TÆT KNOP POST LEBORD BEN HØST SKIB GAS KRUS KOST BØFFÅR SMØR GÆST SKUR IS TAG MØRK STENSNE KRUS LÅS STÅ BRUN DANS SANG KORT



Dantale 1 Word lists 33-40List 1 List 2 List 3 List 4 List 5 List 6 List 7 List 8HVID SOK KLAP TAG FISK GÅS STÅ SKIBPIND TAND HÆL NYT KÆLK GRÅ PÆL VÅDKROG LUFT STOR LØN DAMP SENG TOM HJULSTOL VÆGT BÅL GARN NÆB GÅRD DØGN NYSØM KLAT KORN MÆLK SØM NYT NÆB LUFTTUR VAT LE TELT SKUR DYB STEN SOKNØD SKO SØD GLAS NET GRØN SØVN BYFLOT HAT KNÆ HALM SØD HØST BORD KORTTÆT SENG TRÅD POST STOR PRIK KANT SNEGRÅ MÅL RIST HAT SNOR NÅ MAD BANKNAVN AND KRUS PÆN VÅD FLÅ HUND TRÅDMUND RIS PRIK ARM DAL BUS FLOT TELTPELS SKIB NAVN SKO SALT VÆG SMØR SØHAVN SOL BØF DØGN HJUL SAKS FLOD HÅRGRÆS SE BUS SORT VÆGT KROG NAT HALMTØJ GRØD MYG BEN KORT STOL RIST DYRSLOT ØL SMÅ MÅL DÆK HUS SE MYGBORD DÆK BÆNK SKIB MAND HÆL VÆGT KALKSKUD PRIS JAGT FÅR SOK BEN RENT HATRENT KAT NÅL FLOD BÆNK NAVN ILD TANDARM SPOR KURS SKUD MYG SMAL STOR TRÆTMAND FLÅ PIND KOST IS PAS VINK VANDVÅD MAD DEL REGN VAND VAT HORN BREDGRØN PROP SMØR HVID DEL KOST DÆK SLOTPOST BANK SØ ARK SMÅ FOD LÅS PAS


F DANTALE 2 SENTENCE LISTS 106

F Dantale 2 Sentence ListsList 1

Ingrid finder syv røde huseMichael ejer tyve pæne ringeLinda låner seks flotte skabeUlla får fjorten hvide jakkerNiels solgte ti store maskerHenning ser ni smukke planterAnders vandt otte sjove gaverKirsten købte tre nye blomsterPer valgte tolv fine bilerBirgit havde fem gamle kasser

List 2Ulla solgte ti røde bilerLinda ejer tre hvide blomsterAnders havde tolv pæne kasserMichael valgte otte fine maskerNiels vandt fjorten store jakkerBirgit finder ni nye ringeHenning låner syv sjove skabeIngrid ser fem flotte planterKirsten købte seks smukke gaverPer får tyve gamle huse

List 3Per ser seks pæne planeterNiels ejer tyve hvide bilerKirsten havde fem store maskerUlla finder otte nye jakkerLinda vandt ni røde skabeMichael får ti flotte gaverHenning valgte tre gamle ringeAnders købte syv fine kasserIngrid låner tolv sjove huseBirgit solgte fjorten smukke blomster

List 4Anders vandt tolv store kasserPer købte ti fine bilerUlla ejer syv røde jakkerMichael havde fem nye planterNiels solgte tre smukke blomsterLinda valgte ni hvide skabeBirgit finder tyve pæne huseIngrid låner otte gamle maskerHenning får seks flotte ringeKirsten ser fjorten sjove gaver


List 5Henning låner syv hvide jakkerAnders finder fem gamle skabeLinda havde ti fine gaverKirsten solgte seks sjove ringeMichael får tolv røde huseBirgit ser tre store blomsterNiels købte tyve pæne planterPer valgte ni flotte maskerUlla vandt otte smukke bilerIngrid ejer fjorten nye kasser

List 6Henning havde fjorten sjove blomsterKirsten ser syv store huseLinda finder fem nye maskerUlla købte tyve hvide jakkerMachael får tolv smukke planterAnders ejer seks flotte bilerNiels låner ti fine gaverPer solgte ni gamle ringeBirgit valgte tre røde skabeIngrid vandt otte pæne kasser

List 7Anders finder seks store gaverMichael ser tyve gamle blomsterKirsten vandt tolv flotte ringeIngrid valgte otte hvide planterBirgit får fem fine maskerUlla låner syv sjove skabeHenning hvade tre nye huseLinda solgte fjorten røde kasserNiels ejer ti smukke bilerPer købte ni pæne jakker

List 8Niels ser ti fine jakkerPer får tolv store kasserMichael vandt tre nye skabeAnders ejer tyve flotte gaverHenning låner fem smukke ringeLinda havde seks sjove maskerKirsten købte fjorten pæne planterUlla finder otte gamle blomsterIngrid valgte ni røde bilerBirgit solgte syv hvide huse


List 9Linda havde ti fine blomsterUlla låner tre flotte ringePer finder fem store maskerMichael vandt syv smukke bilerIngrid valgte fjorten sjove jakkerKirsten får otte hvide kasserHenning solgte tolv gamle gaverNiels ejer tyve pæne huseAnders købte ni nye planterBirgit ser seks røde skabe

List 10Niels finder tyve smukke skabeHenning valgte tolv store kasserLinda låner fjorten gamle bilerBirgit vandt fem fine huseIngrid købte ni hvide planterAnders ser seks røde jakkerMichael får tre nye maskerKirsten solgte syv sjove blomsterUlla havde otte pæne gaverPer ejer ti flotte ringe

List 11Linda solgte fjorten flotte huseNiels vandt ni hvide blomsterUlla havde tolv røde jakkerKirsten købte seks sjove bilerPer ejer syv store kasserIngrid får otte smukke maskerAnders finder tre pæne gaverBirgit ser ti gamle skabeHenning låner tyve nye planterMichael valgte fem fine ringe

List 12Ulla ejer fem røde jakkerBirgit får tre store planterLinda solgte otte flotte huseMichael havde fjorten fine kasserKirsten ser ni pæne ringeNiels finder tyve gamle maskerAnders valgte seks sjove gaverHenning låner syv smukke skabeIngrid købte tolv hvide bilerPer vandt ti nye blomster


List 13Linda ejer fjorten hvide jakkerHenning havde ni nye gaverUlla købte ti store bilerPer finder fem fine huseIngrid ser tre smukke maskerNiels vandt seks flotte blomsterAnders får syv pæne planterBirgit valgte tolv gamle skabeMichael solgte tyve sjove kasserKirsten låner otte røde ringe

List 14Per valgte otte pæne maskerMichael ejer seks nye huseLinda solgte fem store kasserNiels købte fjorten gamle jakkerAnders vandt tre fine blomsterBirgit ser tolv røde skabeKirsten får ni smukke ringeIngrid låner ti flotte planterHenning havde syv hvide bilerUlla finder tyve sjove gaver

List 15Per får otte flotte blomsterKirsten ejer syv fine ringeLinda havde fem smukke huseIngrid valgte seks nye bilerNiels ser ni pæne skabeMichael solgte fjorten gamle planterUlla finder tre store maskerHenning låner tyve hvide kasserAnders købte tolv sjove jakkerBirgit vandt ti røde gaver

List 16Henning vandt syv flotte skabePer ser otte røde jakkerNiels ejer tre sjove kasserKirsten havde tolv store ringeUlla får tyve pæne planterAnders finder ni smukke gaverLinda købte fjorten nye huseIngrid låner fem hvide bilerBirgit valgte seks fine blomsterMichael solgte ti gamle masker

G DANTALE MATERIAL LIST DISTRIBUTION OVERVIEW 110

G Dantale Material List Distribution Overview

Dantale Material List Distribution For CDs 1-4Classroom Auditorium

Track Dantale Real, CD1 Simulated, CD3 Real, CD2 Simulated, CD41 1 List 9 List 33 List 21 List 52 1 List 10 List 34 List 22 List 63 1 List 11 List 35 List 23 List 74 1 List 12 List 36 List 24 List 85 1 List 13 List 37 List 25 List 406 1 List 14 List 38 List 26 List 397 1 List 15 List 39 List 27 List 388 1 List 16 List 40 List 28 List 379 1 List 17 List 1 List 29 List 3610 1 List 18 List 2 List 30 List 3511 1 List 19 List 3 List 31 List 3412 1 List 20 List 4 List 32 List 3313 2 Lists 13,14,15 Lists 3,2,1 Lists 9,10,11 Lists 16,15,1414 2 List 1 List 16 List 13 List 415 2 List 2 List 15 List 14 List 316 2 List 3 List 14 List 15 List 217 2 List 4 List 13 List 16 List 118 2 List 5 List 12 List 8 List 1019 2 List 6 List 11 List 7 List 820 2 List 7 List 10 List 6 List 1121 2 List 8 List 9 List 5 List 722 2 List 9 List 8 List 4 List 1223 2 List 10 List 7 List 3 List 624 2 List 11 List 6 List 2 List 1325 2 List 12 List 5 List 1 List 5

Table 27: Dantale material list distribution for the four CDs used for each of theroom scenarios.

H FLYER 111

H Flyer

Figure 43: Test Subject Recruitment Flyer

I QUESTIONNAIRE 112

I Questionnaire

Figure 44: Questionnaire.

J REAL-ROOM LOUDSPEAKER CALIBRATION VALUES 113

J Real-Room Loudspeaker Calibration Values

Real-Room Loudspeaker Calibration ResultsClassroom 019/352 Auditorium 021/341

Test subject Noise Speech SNR Noise Speech SNR1 69.9 dB 70.0 dB 0.1 dB 69.9 dB 70.2 dB 0.3 dB2 69.9 dB 70.0 dB 0.1 dB 69.9 dB 70.2 dB 0.3 dB3 70.2 dB 70.5 dB 0.3 dB 70.1 dB 70.0 dB -0.1 dB4 70.1 dB 70.0 dB -0.1 dB 70.3 dB 70.4 dB 0.1 dB5 70.1 dB 70.0 dB -0.1 dB 70.4 dB 70.5 dB 0.1 dB6 70.0 dB 69.9 dB -0.1 dB 70.4 dB 70.5 dB 0.1 dB7 70.1 dB 69.9 dB -0.2 dB 70.2 dB 70.4 dB 0.2 dB8 69.8 dB 69.6 dB -0.2 dB 70.3 dB 70.4 dB 0.1 dB9 69.7 dB 69.9 dB 0.2 dB 69.8 dB 69.6 dB -0.2 dB10 69.7 dB 69.9 dB 0.2 dB 70.2 dB 70.4 dB 0.2 dB11 69.8 dB 69.6 dB -0.2 dB 70.2 dB 70.2 dB 0.0 dB12 69.8 dB 69.9 dB 0.1 dB 69.8 dB 69.7 dB -0.1 dB13 69.9 dB 69.9 dB 0.0 dB 70.2 dB 70.4 dB 0.2 dB14 70.0 dB 70.1 dB 0.1 dB 70.4 dB 70.2 dB -0.2 dB15 70.0 dB 70.1 dB 0.1 dB 69.9 dB 69.7 dB -0.2 dB

Table 28: Real-room loudspeaker calibration values for the classroom and the au-ditorium. The resulting SNR from the noise and the speech loudspeakersources can also be seen.

K TEST SUBJECT INTELLIGIBILITY SCORE SHEET 114

K Test Subject Intelligibility Score Sheet

The full test subject intelligility score sheet can be found on the supplied CD.Table 29 and 30 contain an example of the a filled score sheet for Dantale 1and Dantale 2 material.

CD 1, tracks 1-3, Real Classroom 019, Position 1Word Track 1, -3 dB Track 2, 0 dB Track 3, -3 dB1 Salt X Skov X Væg X2 Spor X Krus Klat3 Halm X Sol X Sok X4 Gås X Hvid X Sne X5 Mørk X Vagt X Hals X6 Telt Horn X Bord7 Hår X Spil X Jagt X8 Pil X Råb Skur9 Flod X Kort X Ris10 Smal X Se X Dæk X11 Brød X Garn X Fisk X12 Kat Rent X Hjem X13 Tung Mad X Flå14 Stok X Sko X Mål15 Mel X Brun X Kant X16 Mund X Gå Pris X17 Brev X Mælk X Del X18 Skind X Sten X Båd X19 Gård X Dyb Vogn X20 Ben X Hjul X Tøj X21 Græs X Seng Spand X22 Øl X Arm Slå X23 Jord X Fart X Løn24 Ged X Slot X Vat25 Net X Smør X Hårdt XTotal correct 22/25 - 88% 19/25 - 76% 17/25 - 68%

Table 29: Excerpt from the test subject intelligibility score sheet. This scoresthe Dantale 1 material for CD 1, tracks 1 to 3 for position 1 for theclassroom 019/352.

K TEST SUBJECT INTELLIGIBILITY SCORE SHEET 115

CD 4, track 22, Simulated Auditorium 021, position 2, SNR -4 dBWord 1 Word 2 Word 3 Word 4 Word 5 Correct words

Ingrid X finder X syv X røde huse 3Michael X ejer X tyve X pæne ringe X 4Linda låner seks X flotte X skabe X 3Ulla X får X fjorten X hvide X jakker X 5Henning ser X ni X smukke planter 2Anders X vandt X otte sjove X gaver X 4Kirsten X købte tre nye X blomster X 3Per valgte tolv fine biler X 1Birgit X havde X fem X gamle X kasser X 5

30/50 - 60%

CD 4, track 23, Simulated Auditorium 021, position 2, SNR -6 dBWord 1 Word 2 Word 3 Word 4 Word 4 Correct Words

Ulla X solgte ti X røde biler X 3Linda ejer tre X hvide blomster X 2Anders X havde tolv X pæne X kasser 3Michael X valgte X otte X fine X masker 4Niels vandt X fjorten X store X jakker X 4Birgit X finder X ni nye ringe 2Henning låner syv sjove skabe 0Ingrid X ser fem X flotte X planter 3Kirsten X købte seks smukke gaver 1Per X får tyve gamle huse X 2

24/50 - 48%

Table 30: Excerpt from the test subject intelligibility score sheet. This scoresthe Dantale 2 material for CD 4, track 22 and 23 in position 2 for theauditorium 021/341

.

L DANTALE 1 RESPONSE SHEET 116

L Dantale 1 Response Sheet

CD 2 Real Audiorium, Position 1Word Track 4 Track 5 Track 612345678910111213141516171819202122232425Total correct

Table 31: Excerpt from the Dantale 1 response sheet. There is a response sheetfor each of the four room scenarios.

M APPENDIX CD CONTENTS 117

M Appendix CD Contents

A CD containing additional material relevant to this project is attached atto the back of this report.

The CD contains:

• A PDF version of the report.

• ODEON models for both the classroom 019/352 and auditorium 021/341.

• The test subject score sheet.

• The Dantale 1 response sheet.

• Matlab code for processing the measurement results.

Documents

Comparison of Speech Intelligibility Measurements with ...etd.dtu.dk/thesis/242416/SebastianAlexDalgas_Comparison_of_Speec… · Comparison of Speech Intelligibility Measurements