Directional Sound (DS) Psychoacoustic Basis & Implementation

Directional Sound Directional Sound (DS)Psychoacoustic Basis & ImplementationPsychoacoustic Basis & Implementation

Daniel J. O’Connor, P.E., FSFPEVice President – EngineeringSchirmer Engineering Corporation

222

Background

Professor Deborah Withington

Auditory neuroscience, University of Leeds

Expertise needed

Human behavior – Dr. G. Proulx, Dr. John Bryan

Acoustics – Robert Elfering, P.E./Shiner Associates

FP/LS design – Schirmer Engineering

Reviewed all published literature and human subject tests on DS

Reviewed key texts on sound & psychoacoustics

333

Basic Findings

Sound & psychoacoustic theory is well established

Significant work has been done that demonstrates the benefits of using DS

Implementation is relatively easy compared to other exit-assist technologies

444

How Does It Work?

Human hearing can readily process sound information

Narrowband sounds can be ambiguous

Broadband sound greatly enhances localization cues

Ear Canal Semicircular canals

Temporal bone Round window

Malleus Vestibule

Incus Vestibular nerve

Eardrum Cochlea

Stapes Eustachian tube

11

12

10

555

How Sound Localization Works

AIR PARTICLES MOVEDBY VIBRATING OBJ ECT

INTERAURAL TIME DIFFERENCE

666


0

-5

-10

LOU

DN

ESS D

IFFER

EN

CE IN

DEC

IBELS

100 500 1000 5000

-15

-20

-25

-30

-3510,000 20,000

FREQUENCY IN CYCLES PERSECOND

PURE TONE

INTERAURAL INTENSITY DIFFERENCES - LOUDNESS AS FUNCTION OF FREQUENCY

DIFFERENCE IN LOUDNESS-LEVELS AT THE TWO EARS WHEN PURE TONES OFVARIOUS FREQUENCIES COME DIRECTLY FROM THE SIDE. THE CURVEILLUSTRATES HOW SOUND-SHADOW OF THE HEAD CHANGES INTENSITY ATVARIOUS FREQUENCIES. (SOURCE: HEARING ITS PSYCHOLOGY ANDPHYSIOLOGY, AMERICAN INSTITUTE OF PHYSICS)

777


4

2

0

-2

-4

-6

-8

DEC

IBEL

S

NEAREAR

FAR EAR

DIFFERENCE

ANGLE IN DEGREES40200 60 80 100 120 140 160 180

THE CURVES SHOW THE VARYING LOUDNESS-LEVELS AS A SPEECH SOURCE ISROTATED AROUND THE HEAD. ALTHOUGH THE DIFFERENCE AT 42 AND 137DEGREES IS IDENTICAL, THE SOUND QUALITY DIFFERS BECAUSE THE HEADAND OUTER EAR DISTORTS THE SOUND DIFFERENTLY WHEN COMING FROMTHE FRONT OR BACK. (SOURCE: HEARING ITS PSYCHOLOGY AND PHYSIOLOGY,AMERICAN INSTITUTE OF PHYSICS)

INTERAURAL DIFFERENCE - FRONT-TO-BACK, HRTF EFFECT

42 137

888

Broadband Sound Benefit

Broadband sound is complex & provides sound differences not found with narrowband frequencies

■ Loudness

■ Intensity

■ Spectrum

Redundant sound cues combined with head motion allows for easy localization

“Precedence Effect” – ear discerns and fixates on first sound and consequently no problem in highly reverberant spaces

999

Broadband Sound Benefit

Typical 3,000 Hz alarm dominates and DS need not be higher in overall sound pressure level

Clearly distinguished from standard notification devices (bells, horns)

Voice systems require additional considerations but can be integrated

Directional Sound vs. Fire Alarm Signal (3Khz)Directional Sound at 66dBA and Fire Alarm horn at 86dBA

Measured at 10' horizontally in a anechoic room

0102030405060708090

100110

0 5000 10000 15000 20000

Frequency (Hz)

dB

3000 Hz

101010

How Can DS Help an Evacuation

Not intended to replace, but rather be Not intended to replace, but rather be compatible with standard fire alarmscompatible with standard fire alarms

Focus is providing additional sound cues to Focus is providing additional sound cues to assist occupants in locating the assist occupants in locating the exitexit

““Attention capturing capabilityAttention capturing capability” overcomes ” overcomes issues of “issues of “learned irrelevance”learned irrelevance” of exit signs of exit signs

Sound travels around corners avoids issues Sound travels around corners avoids issues of line-of-sight methods (e.g. exit signs)of line-of-sight methods (e.g. exit signs)

Sound independent of languageSound independent of language

Provides cues in adverse conditions of Provides cues in adverse conditions of smoke or other low visibility conditionsmoke or other low visibility condition

111111

Audience Demonstration

121212

Influence on Human Behavior

University of University of Strathclyde TrialsStrathclyde Trials

Isle of Arran ferry Isle of Arran ferry crew quarterscrew quarters

4 trials – 3 exits 4 trials – 3 exits available, 3% available, 3% smoke, 9-17% exit smoke, 9-17% exit time improvementtime improvement

6 trials – 1 exit only, 6 trials – 1 exit only, 3% smoke, 47-71% 3% smoke, 47-71% exit time exit time improvementimprovement

131313

Influence on Human Behavior University of Strathclyde University of Strathclyde

TrialsTrials

Caledonian Isles restaurant Caledonian Isles restaurant and lounge areaand lounge area

With DS trials 95% of With DS trials 95% of subjects indicated sound subjects indicated sound guided them to an exit, 85% guided them to an exit, 85% indicated DS was most indicated DS was most helpful aidhelpful aid

With smoke trials With smoke trials 85% prefer sound over LLL 15% preferred both

No smoke trialsNo smoke trials 73% preferred sound over LLL 22% preferred LLL

141414

Understanding Basic Egress Concepts

Exit access Exit Exit discharge Refuge area, area of refuge, or area of rescue

assistance Horizontal exit Exit passageway Dead-end corridor Common path-of-travel

151515

What Defines Egress, Escape and Refuge Elements

National Fire Protection Association NFPA 101, Life Safety Code

NFPA 5000,

Building Construction & Safety Code

NFPA 1, Uniform Fire Code

Other NFPA documents

International Code Council, Inc. International Building Code International Fire Code International Existing Building Code International Performance Code for

Buildings and Facilities

161616

Federal Accessibility Laws

Americans with Disabilities Act Accessibility Guidelines (ADAAG)

Fair Housing Accessibility Guidelines (FHAG)

171717

Key Definition - “Exit”

NFPA Definition

Exit - That portion of a means of egress that is separated from all other spaces of a building or structure by construction or equipment as required to provide a protected way of travel to the exit discharge.

ICC Definition

Exit - That portion of a means of egress that is separated from other interior spaces of a building or structure by fire-resistance-rated construction and opening protectives as required to provide a protected path of egress travel between the exit access and the exit discharge. Exits include exterior doors at ground level, exit enclosures, exit passageways, exterior exit stairs, and horizontal exits.

181818

Types of “Exits” – Familiar Types

Doors leading directly to the outside at grade Interior stairs enclosed by fire rated

construction, which includes Smokeproof towers Pressurized stairways

Exterior stairs isolated from the building interior with fire rated or protective construction

Fire escapes

191919

What are the Exits?

ENCLOSEDEXIT STAIR

EXIT ACCESSENDS AT EXITDOOR

up

dow

n

up dow

n

ENCLOSEDEXIT STAIR

XX

X

EXIT ACCESS STARTS ATANY POINT

X

X

X

EXIT ACCESSROUTES

202020

Possible Stair Exit Arrangementsu

p dow

n

FIRE DOOR

FIRE RATED ENCLOSEDSTAIRWAY

OPEN TO OUTSIDE

up do

wn

FIRE DOOR


FIRE DOOR

up do

wn

FIRE DOOR

MECHANICALVENTILATION

SHAFT


212121

What are the Exits?

EXTERIOR EXITSTAIRWAY

EXIT(FROM GRADE LEVEL)

INTERIOR EXITSTAIRWAY

EXIT DISCHARGE

222222

Types of “Exits” – Others Types to Recognize

Passageways enclosed by fire rated construction (should not be confused with corridors)

Horizontal exits Ramps enclosed by fire rated construction Escalators enclosed by fire rated construction Other special exits – may be result of code equivalency

or a performance based design, or otherwise negoitiated concept

232323

Horizontal Exit

2 HOUR FIRE BARRIER DOORS ARE AUTOMATICOR SELF CLOSING FIRE DOORS

up

down

up

down

ENCLOSED EXITSTAIR

ENCLOSED EXITSTAIR

242424

Exit Passageway

FIRE RATING BASED ONNUMBER OF STORIES

up

down

up do

wn

FIRE RATED EXIT PASSAGEWAY(PENETRATIONS RESTRICTED)

CORRIDOR

FIRE RATED DOOR

252525

Areas of Refuge(most commonly required in nonsprinklered new construction)

up do

wn

30"x 48" WHEELCHAIR SPACE

AREA OF REFUGE IN AMEANS OF EGRESS

STAIRWAY

48" MINIMUM

48" MINIMUM

up

down

30"x 48" WHEELCHAIR SPACE

AREA OF REFUGEADJACENT TO MEANS OFEGRESS STAIRWAY

48

" M

INIM

UM

48

" M

INIM

UM

262626

Dead-End & Common Path-of -Travel

272727

Locations not Suitable for Directional Sounders

Windows for Rescue Stairway that is an Incomplete route Exterior door that leads to a outdoor locked

fenced area Portable ladders, rope fire escapes and similar

escape devices NFPA and ICC documents state that access to an

exit shall not pass through a high-hazard occupancy, a kitchen, a storeroom or a closet

282828

Installation/Use Concepts – Type 1

Type 1 Installation– most basic, straightforward installation

Locate at entry point to EXITS, Refuge Areas Set to fastest pulse pattern at EXIT Set to slow pulse at “area of refuge” Use “area of refuge” supplemental indicator May need additional sounders to address intervening doors Incorporate into Emergency Plans for facility

292929

ENCLOSEDEXIT STAIR

updow

n

ENCLOSEDEXIT STAIR

up

dow

n

AREA OFREFUGE

AREA OFREFUGE

SOUNDER SET TO“FAST” PULSE TOMARK EXIT STAIR

SOUNDER SET TO “FAST” PULSE PLUSREFUGE TONG TO MARK ENTRANCETO EXIT STAIR AND ADJOINING AREAOF REFUGE

SOUNDER SET TO “SLOW” PULSEPLUS REFUGE TONG TO MARK AREAOF REFUGE THAT IS NOT AN EXIT

KEY

EXIT SIGN SHADED QUADRANT REPRESENTSVISIBLE FACE

EXIT SIGN WITH DESIGNATION OF DIRECTIONALARROW

DIRECTIONAL SOUNDER

FULL HEIGHT WALLS

PARTIAL HEIGHT DIVIDERS

Implementation

303030

InstallationInstallationat Doorsat Doors

FLOOR

CEILING

CENTER LINEOF DEVICE

2 FT.

WHERE LIMITEDWALL SURFACESARE AVAILABLE, ACEILING MOUNTINSTALLATIONWITH DIRECTIONALSOUNDER NOMORE THAN 2 FEETDISTANCE OFFFACE OF DOOR

EXAMPLELOCATIONS FORDIRECTIONALSOUNDERS

SIDE VIEW

FLOOR

CEILING

FRONT VIEW

313131

Open Floor Plan Example

KEY

EXIT SIGN SHADED QUADRANT REPRESENTSVISIBLE FACE

EXIT SIGN WITH DESIGNATION OF DIRECTIONALARROW

DIRECTIONAL SOUNDER

FULL HEIGHT WALLS

PARTIAL HEIGHT DIVIDERS

up

down

up

down

COMMON PATH OF TRAVEL

DE

AD

-EN

DD

EA

D-E

ND

IN OPEN-PLAN FLOORS, TYPE 2SOUNDERS SHOULD NOT BE USED FOROTHER THAN DEAD-ENDS OR COMMONPATH OF TRAVEL CONDITIONS.MULTIPLE SOUNDERS IN THE COMMONEGRESS ROUTE OF AN OPEN FLOORPLAN WOULD RESULT IN CONFLICTINGDIRECTIONAL SOUND CUES. TYPE 1SOUNDERS MAY NEED TO HAVE THEPOWER SETTING INCREASED FORBETTER PENETRATION INTO THE OPENFLOOR SPACE.

323232

Intervening Door

FIRE RATING BASED ONNUMBER OF STORIES

up

down

up dow

n

CORRIDORSET DIRECTIONALSOUNDER TO “FAST”PULSE PATTERN

INTERVENING DOOR

ADDITIONAL SOUNDER SET TO “FAST” PULSE TO INCREASE THE DIRECTIONAL SOUND PENETRATIONINTO THE CORRIDOR ONCE THE THE INTERVENING DOOR CLOSES. THE SOUNDER SHOULD BE LOCATEDON THE CORRIDOR SIDE OF THE DOOR. ONCE THE EVACUEES PASS THROUGH THE DOOR THEY WILLBEGIN TO HEAR THE SOUNDER AT THE STAIRWELL AND PROCEED TOWARDS THE ACTUAL EXIT.

333333

Installation/Use Concepts – Type 2

Type 2 Installation – enhanced installation, additional sound cues along egress path for occupants

Locate at entry point to EXITS, Refuge Areas same as Type 1 installation, and

door from a room/area having a common path-of-travel, the outlet end of a dead-corridor,

At points of multiple route choice where a directional sound device is located leading in the direction of the nearest exit

At points along a route where the sounder at the exit is not audible Use additional directional sounders where they will enhance the ability of

occupants to locate exits and the direction thereto Use increasing speed in pulse patterns in moving from sounder locations

most distant from the exit (slower pulse) to sounders nearer the exit (faster pulse). Maximum of 4 sounders along path (only 4 pulse settings)

Incorporate into Emergency Plans for facility

343434

Type 2 Installation

ENCLOSED EXIT STAIR

up

down

‘FAST’ PULSE

KEY

DIRECTIONAL SOUNDER

FULL HEIGHT WALLS

‘MEDIUM 1’ PULSE


‘SLOW’ PULSE


SAME PULSE OK IF NOTSAME ROUTE TO EXIT

NOT MORE THAN FOURSOUNDERS ALONG SAMEROUTE TO EXIT

353535

Corridor Corners 2 FT.

DIRECTION OF TRAVEL TOTHE NEAREST EXIT

CENTER LINE OF CORRIDOR

PREFERRED INSTALLATIONZONE

ACCEPTABLEINSTALLATION ZONE

DIRECTION OF TRAVEL TOTHE NEAREST EXIT

363636

Dead End Corridors

373737

Don’t Use a Type 2 Installation

Do not use a Type 2 installation for open floor plans with multiple exits, where sounders will tend to conflict with each other

Do not use a Type 2 installation where occupant loads and exit capacities are not reasonably balanced with travel distances to routes

383838

Example – When Not to Use Type 2KEY

EXIT SIGN SHADED QUADRANTREPRESENTS VISIBLE FACE

EXIT SIGN WITH DESIGNATION OFDIRECTIONAL ARROW

DIRECTIONAL SOUNDER

FULL HEIGHT WALLS

CONSIDERATIONS FOR OCCUPANT LOAD BALANCE:ALTHOUGH ROUTE A IS THE SHORTEST TRAVELDISTANCE TO AN EXIT, TYPE 2 SOUNDERS ARE NOTRECOMMENDED TO BE LOCATED ALONG ROUTE ADUE TO THE LIMITED EXIT CAPACITY. WHEREOCCUPANT BALANCE ISSUES MAY BE PRESENT, ITIS RECOMMENDED THAT DIRECTIONAL SOUNDERSBE LIMITED TO A TYPE 1 INSTALLATION (EXITSONLY).

KEY DECISIONPOINT

KEY DECISIONPOINT

RO

UT

E A

EXIT EXIT

EXIT

AUDITORIUM(400 OCCUPANTS)

393939

Contrast of Occupancy Considerations

Retail – visual clutter, patrons not familiar with the variety of exits

Directional sound can be a benefit

Hospitals – highly trained staff, defend-in-place occupancy

Directional sound –NOT appropriate

404040

For More Information

http://www.systemsensor.com/exitpoint/

NFPA Journal May/June 2005

http://www.soundalert.com/

414141

Thanks & Appreciation

Questions ?

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Directional Sound (DS) Psychoacoustic Basis & Implementation