Acoustical Testing: Facts and

MisconceptionsMichael L. MackerethArchitectural Testing

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Presentation Outline

Basic Acoustics

Test Methods

Effects on Sound Transmission Loss

Codes and Regulations

Acoustical Lab

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OITC vs. STC

OITC (Outdoor-Indoor Transmission Class)

Calculated in accordance with ASTM E 1332 (Published in 1990)

Created to provide a single number rating for façades (exterior walls) and façade elements (windows and doors) that are subjected to transportation noises

The OITC is calculated over the frequency range of 80 to 4000 hertz

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OITC vs. STC

STC (Sound Transmission Class)Calculated in accordance with ASTM E 413 (Published in 1970)Created to provide a single number rating for interior building partitions that are subjected to noises from speech, television, radio and office equipment

Note: ASTM E 413 specifically states that the STC calculation should not be used to evaluate partitions exposed to machinery, industrial and transportation noise such as motor vehicles, aircraft and trains.

The STC is calculated over the frequency range of 125 to 4000 hertz

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Basics of Sound Transmission Loss

Source RoomSPL Level = 100 dB

AverageNoise

Reduction of 45 dB

Receive RoomSPL Level = 55 dB

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Flanking Effects onSound Transmission Loss

Source RoomSPL Level = 100 dB

Receive RoomSPL Level = 65 dB

AverageNoise

Reduction of 35 dB

AverageNoise

Reduction of 35 dB

Average NoiseReduction of 45 dB

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Element #1 Exterior Wall Element #2

Window

Element #4 - Roof

Element #3 Door

Roof Soffits

Basement Windows

Floor System

Ceiling System

Gable VentsAttic Fans or Roof Vents

Oven Fans

Chimney

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Sound Pressure Level

N/m2 (Pa) dB Noise Sources100,000 200 Saturn Rocket10,000 180 After Burning Jet Engine1,000 160 Jet Aircraft Engine100 140 Threshold of Pain10 120 Near Elevated Train1 100 OSHA Limit

0.1 80 Industrial Noise0.01 60 Normal Speech0.001 40 Quiet Office

0.0001 20 Whisper0.000002 0 Threshold of Hearing

Sound Pressure Level, Lp = 20 log10 (p(t) / pref)

Where:p(t) = instantaneous sound pressure, Papref = reference sound pressure, standardized at 2 x 10-5 N/m2 (20uPa)

Sound Pressure Level, Lp

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Sound Pressure Level vs. Loudness

Change in Change inDecibels Perceptable Loudness

1 dB Imperceptable change3 dB Just barely distinguishable5 dB 25% Change in Loudness

10 dB 50% Change in Loudness15 dB 63% Change in Loudness20 dB 75% Change in Loudness

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Estimated Window & Curtain Wall Performance

Primary Glazing OnlyWindow/Curtain Wall IG Glazing OITC STC

2.3 mm (3/32 in) annealed, 12 mm (1/2 in) air space, 2.3 mm (3/32 in) annealed 20-22 25-27

3 mm (1/8 in) annealed, 12 mm (1/2 in) air space, 3 mm (1/8 in) annealed 23-25 27-29

3 mm (1/8 in) annealed, 12 mm (1/2 in) air space, 4.8 mm (3/16 in) annealed 25-27 29-31

3 mm (1/8 in) annealed, 12 mm (1/2 in) air space, 4.8 mm (3/16 in) laminated 26-28 31-33

3 mm (1/8 in) annealed, 12 mm (1/2 in) air space, 6 mm (1/4 in) annealed 26-28 31-33

3 mm (1/8 in) annealed, 12 mm (1/2 in) air space, 6 mm (1/4 in) laminated 27-29 32-34

4.8 mm (3/16 in) annealed, 12 mm (1/2 in) air space, 4.8 mm (3/16 in) annealed 25-27 30-32

6 mm (1/4 in) annealed, 12 mm (1/2 in) air space, 6 mm (1/4 in) annealed 26-28 31-33

6 mm (1/4 in) annealed, 12 mm (1/2 in) air space, 6 mm (1/4 in) laminated 28-30 34-36

6 mm (1/4 in) laminated, 12 mm (1/2 in) air space, 6 mm (1/4 in) laminated 29-31 37-39

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Estimated Window & Curtain Wall Performance

Primary & Secondary Glazing

Prime Window/Curtain Wall IG GlazingPrime to

Secondary Air Space

Secondary Window/ Curtain Wall

GlazingOITC STC

3 mm (1/8 in) annealed, 12 mm (1/2 in) air space, 3 mm (1/8 in) annealed 50 mm (2 in) 3 mm (1/8 in)

annealed 28-30 39-41

6 mm (1/4 in) annealed, 12 mm (1/2 in) air space, 3 mm (1/8 in) annealed 50 mm (2 in) 6 mm (1/4 in)

annealed 32-35 42-44

6 mm (1/4 in) laminated, 12 mm (1/2 in) air space, 3 mm (1/8 in) annealed 50 mm (2 in) 6 mm (1/4 in)

annealed 34-36 43-45

6 mm (1/4 in) laminated, 12 mm (1/2 in) air space, 3 mm (1/8 in) annealed 50 mm (2 in) 6 mm (1/4 in)

laminated 35-37 44-46

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Estimated Exterior Wall Performance

Exterior Wall ConstructionOITC Rating

STC Rating

Vinyl siding, OSB board, 2 x 4 wood studs, ½” drywall, no insulation 22 - 24 34 - 36

Vinyl siding, OSB board, 2 x 4 wood studs, ½” drywall, with R-13 insulation 24 - 25 36 - 38

Vinyl siding, OSB board, 2 x 6 wood studs, ½” drywall, no insulation 34-35

Vinyl siding, OSB board, 2 x 6 wood studs, ½” drywall, with R-13 insulation 37-38

Wall Construction

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Sound Transmission Loss Variables

Mass of materialsHeavier materials have higher sound transmission loss.Resonant frequency of the materials or surfacesMost materials will resonate at a certain frequency when they are excited by sound waves or vibrations. The sound transmission loss will decrease at that frequency and probably at some of the surrounding frequencies.Air space between materials or surfacesLarger air spaces yield better performance.Material stiffnessLimper materials provide better noise attenuation. Gypsum Board walls need to be conditioned at 40-70% R.H. for at least 72 hours.Structural coupling between materials and surfacesDecoupling surfaces from each other improves sound transmission loss. Fasteners can affect panel stiffness and coupling between surfaces.Cavity InsulationInsulating stud cavities improves the noise reduction of wall systems.Dissimilar MaterialsUse of dissimilar materials can reduce coincidence dip effects.

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Acoustical Test Methods

AAMA 1801, Voluntary Specification for the Acoustical Rating of Windows, Doors and Glazed Wall Sections

ASTM E 1425, Standard Practice for Determining the Acoustical Performance of Exterior Windows and Doors

ASTM E 90, Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements

ASTM E 336, Standard Test Method for Measurement of Airborne Sound Insulation in Buildings (Field Method – Interior partions or floor to floor)

ASTM E 966, Standard Guide for Field Measurement of Airborne Sound Insulation of Building Facades and Facade Elements (Field Method)

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Effects on Sound Transmission Loss

Window Designs or Components☯

Glass Thickness☯

Air Infiltration☯

Type of Glass (Annealed, Laminated, etc.)☯

Type of Spacer☯

Insulating Glass Films☯

Air Space between Glass Lites☯

Type of Gas Fill☯

Edge Effects

Test Conditions☯

Temperature (For Laminated Glass)

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Fixed Window with 3/4" Insulating Glass

0

5

10

15

20

25

30

35

40

45

10 100 1000 10000

Frequency, Hz.

Soun

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dB

1/8" & 3/32", OITC = 24, STC = 28

1/4" & 1/8", OITC = 27, STC = 31

Glass Thickness Effect on Transmission Loss

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Single Hung Window with Insulating Glass(1/4" annealed, 3/8" Air, 3/32" annealed)

0

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As Received, OITC = 24, STC = 26

Completely Sealed, OITC = 27, STC = 31

Transmission Loss Deterioration Due toAir Leakage

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Sliding Glass Door with Insulating Glass

0

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1/4" Temp / 1/2" Air / 1/4" Temp, OITC = 27, STC = 33

1/4" Temp / 1/2" Air / 1/4" Lami, OITC = 30, STC = 35

1/4" Lami / 1/2" Air / 1/4" Lami, OITC = 31, STC = 38

Tempered vs. Laminated Glass

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Single Hung Window with Insulating Glass(1/4" annealed, 3/8" Argon, 1/8" annealed)

0

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U-Channel Spacer, OITC = 26, STC = 29

Foam Spacer, OITC = 26, STC = 31

Spacer Effect on Transmission Loss

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Insulating Glass with Suspended Films

0.0

10.0

20.0

30.0

40.0

50.0

60.0

10 100 1000 10000

Frequency, Hz.

Soun

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IG without Film, OITC = 22, STC = 28IG with One Film, OITC = 23, STC = 30IG with Two Films, OITC = 24, STC = 31

Transmission Loss ofInsulating Glass withSuspended Films

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Double Hung Window with 1/4" annealed and 1/4" annealed

0.0

10.0

20.0

30.0

40.0

50.0

60.0

10 100 1000 10000Frequency, Hz.

Soun

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1/2" Air Space, OITC = 27, STC = 33

4" Air Space, OITC = 32, STC = 43

Air Space Effect onSound Transmission Loss

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Fixed Window with Insulating Glass (3/16" annealed, 9/16" space, 1/8" annealed)

0

10

20

30

40

50

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10 100 1000 10000Frequency, Hz.

Soun

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Argon Filled, OITC = 24, STC = 30

Air Filled, OITC = 25, STC = 30

Argon vs. Air FilledInsulating Glass

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Codes & Regulations

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Acoustical Requirements & Codes

It is important to verify the acoustical performance of the whole assembly rather than just meeting the performance requirements of the building or glazing elements alone.

The STC and OITC ratings of window and curtain wall units (tested in the laboratory) have been known to be anywhere from three to six points lower than the glass alone data that is prevalent in the fenestration industry.

The difference between a laboratory tested product or assembly and a field tested product or assembly can also vary by three or more points if good construction practices are not followed.

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It is evident that in order to meet the owner's performance expectations, laboratory testing of proposed building elements and field testing of installed assemblies is essential.

It is only at the field testing phase of the process can the true acoustical performance of the assembly can be determined.

Acoustical Requirements & Codes (cont’d)

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International Building Code

SECTION 1207 - SOUND TRANSMISSION

1207.1 Scope. This section shall apply to common interior walls, partitions and floor/ceiling assemblies between adjacent dwelling units or between dwelling units and adjacent public areas such as halls, corridors, stairs or service areas.

1207.2 Air-borne sound. Walls, partitions and floor/ceiling assemblies separating dwelling units from each other or from public or service areas shall have a sound transmission class (STC) of not less than 50 (45 if field tested) for air-borne noise when tested in accordance with ASTM E 90. Penetrations or openings in construction assemblies for piping; electrical devices; recessed cabinets; bathtubs; soffits; or heating, ventilating or exhaust ducts shall be sealed, lined, insulated or otherwise treated to maintain the required ratings. This requirement shall not apply to dwelling unit entrance doors; however, such doors shall be tight fitting to the frame and sill.

1207.3 Structure-borne sound. Floor/ceiling assemblies between dwelling units or between a dwelling unit and a public or service area within the structure shall have an impact insulation class (IIC) rating of not less than 50 (45 if field tested) when tested in accordance with ASTM E 492.

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International Residential Code

APPENDIX K - SOUND TRANSMISSION

AK101.1 General.Wall and floor-ceiling assemblies separating dwelling units including those separating adjacent townhouse units shall provide air-borne sound insulation for walls, and both air-borne and impact sound insulation for floor-ceiling assemblies.

SECTION AK102 - AIR-BORNE SOUNDAK102.1 General. Air-borne sound insulation for wall and floor-ceiling assemblies shall meet a Sound Transmission Class (STC) rating of 45 when tested in accordance with ASTM E 90. Penetrations or openings in construction assemblies for piping; electrical devices; recessed cabinets; bathtubs; soffits; or heating, ventilating or exhaust ducts shall be sealed, lined, insulated or otherwise treated to maintain the required ratings. Dwelling unit entrance doors, which share a common space, shall be tight fitting to the frame and sill.

SECTION AK103 - STRUCTURAL-BORNE SOUNDAK103.1 General. Floor/ceiling assemblies between dwelling units or between a dwelling unit and a public or service area within a structure shall have an Impact Insulation Class (IIC) rating of not less than 45 when tested in accordance with ASTM E 492.

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LEED for Classrooms

Intent

Provide classrooms that are quiet and in which teachers can speak to the class without straining their voices andstudents can effectively communicate with each other and the teacher.

Requirements

Design classrooms and other core learning spaces to meet the Reverberation Time (RT) requirements of ANSIStandard S12.60-2002, Acoustical Performance Criteria, Design Requirements and Guidelines for Schools. Also,design classrooms and other core learning spaces to meet the Sound Transmission Class (STC) requirements,excepting windows, which must meet an STC rating of at least 35.

ANDOPTION 1

Using the methodology described in annexes B through D of ANSI Standard S12.60-2002, achieve a maximumbackground noise level in classrooms and other primary learning spaces of 45 dBA.

OROPTION 2

Design classrooms and other core learning spaces using the methodology listed in the 2003 HVAC ApplicationsASHRAE Handbook, Chapter 47 on Sound and Vibration Control, and achieve an RC (N) Mark II level of 37.

Potential Technologies & Strategies

Design considerations include reducing noise from exterior to interior spaces, between spaces within the building,and within the classroom space. External to internal noise transmission can be reduced by orienting classroomsaway from external noise sources and using thick and/or massive materials in walls and roofs. Also, windowsshould be well sealed and have adequate air gaps between sheets of glass.

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Housing & Urban Development

U.S Department of Housing and Urban Development

Specification No. 24 CFR Part 51

Site Acceptability Standards listed in table below:

Figure 2.6 HUD site acceptability criteria

Day-Night Equivalent Sound Level in Decibels (Ldn)

Acceptable Not exceeding 65 dB

InFigure 2.6, ranges of Ldn arecorrelated withvarious dispositions that classifyHUDapproval procedures and identifythe need for noise abatement, either at the site property line or in the construction of the building exterior. These havebeen devised to achieve the HUD goal for interior noise levels of a day-night equivalent noise level not exceeding 45dB

Normally Unacceptable Above 65 dB but not exceeding 75 dB

Unacceptable Above 75 dB

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Environmental Protection Agency

Specification NEPA Pub. No. 550/9-79-100 (November 1978)

Ldn Leq (24 hrs)

< 45 dB

< 45 dBA

U.S. Environmental Protection Agency

Effect

Sound Pressure Level

Area

Hearing < 70 dBA All areas (at the ear)

Indoor Activity

Indoor residential areas

Other indoor areas with human activities such as schools, etc.

Outdoor Activity

< 55 dBOutdoors in residential areas and farms and other areas wherepeople spend widely varying amounts of time and other places inwhich quiet is a basis for use.

< 55 dBA Outdoor areas where people spend limited amounts of time such as school yards, playgrounds, etc.

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Acoustical Laboratory Control Panel

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Large Reverberation Chamber

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Rotating Vane in Large Reverberation Chamber

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TL Test Frame for Single and Double Doors

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4060 Window Installedin Test Opening

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Questions?