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Sound Design for the multiplexFunctions of Sound

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A noise source in one room resultsfrom an impact of an object onto aseparating surface, such as a floorand transmits the sound to an

adjacent room. A typical examplewould be the sound of footsteps ina room being heard in a roombelow. Acoustic control measuresusually include attempts to isolatethe source of the impact, orcushioning it. For example carpetswill perform significantly betterthan hard floors.

(B) Impact Sound Insulation : the insulationagainst noise originating directly on a structure by blows or vibration e.g.

footsteps above, furniture being moved, drilling and hammering the structure.

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Impact Transmission

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Flanking Transmission A More Complex Form Of Noise Transmission, Where The ResultantVibrations From A Noise Source Are Transmitted To Other Rooms OfThe Building Usually By Elements Of Structure Within The Building.For Example, In A Steel Framed Building, Once The Frame Itself IsSet Into Motion The Effective Transmission Can Be Pronounced.

Problem Good Wall Design But Poor Noise Reduction

Cause Flanking Transmission Along The Top Layer Of A Concrete Floor.

Solutions Avoid Installing Floor Systems That Are Rigidly Connected Under A

Lightweight Wall. Flanking Sound Can Travel Along The Top Layer Or In The Joist ToRadiate In The Room On The Other Side Of The Wall. Eliminate By Introducing A BreakIn The Structure As Shown In Figures.

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o The Intent of Sound Cues

1. Why is the cue there, what is itsfunction?

2. Is the sound associated with aparticular character?

3. What is the psychological intent?

4. What is the period, time and location?

5. Interaction with the actors and theworld of the play

6. Reinforce the action onstage

7. Illustrate and support emotion

8. Create focus

9. Dramaturgy Leitmotif andforeshadowing

o Styles of Sound Design

1. Realistic sounds function as close to reality as

possibleStrong attention paid to factual detail, toilet flushes,

music from

practical (functioning) radios, phone rings; clearlyrepresent reality

May use preshow and intermission music, but littleunderscore

2. Cinematic variation on realismExtensive use of ambience and environment, very

detailed

Involved musical underscoring, leitmotifs forcharacters

3. Representational sparser form of cinematicrealism

Environments introduce scene and then fade out or

use single element to establish locale

Music is more specifically used.

4. Abstract sounds reflect the artists interpretationof the world

Can be impressionistic or expressionistic, design is

conceptualizedSounds are distorted, unnatural or used in a different

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Sound Absorption MeasurementsIn the theatre, 6 mm multiplex panels on a 25mm cavity filled with low-density foam

were used as low frequency, sound absorption material. The absorption of thesetypes of materials relies on the resonance of the panel at a typical frequency. Theabsorption coefficients of the 400 m wooden panels had to be estimated for theODEON prediction model. The resonance frequency was determined by recordingthe sound when tapping on the panels using DIRAC external input and amicrophone.

Wooden panels assound absorption

From the recording, the resonancefrequency of the panels could bedetermined from a clear peak in the FFTspectrum graph. The resonancefrequency of the wooden panels seemedto lie in the 250 Hz octave band(theoretically 200 Hz). This explains theshape of the reverberation time curvewhich has a dip at the 250 Hz octaveband.

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Promising sound absorbing materials weregathered at the nearby market in theslums. These are the only materialsdirectly available to the theatre. One of

these materials is a low-density foam thatis used for cushions and mattresses. Thecushions could be used as baffles and themattresses could be put against walls andceiling.

The sound absorption of the cushions has

been tested in an improvised laboratorysetup in an empty reverberant room insidethe theatre. The baffles proved to be soundabsorbing up to 100% for frequencies from125 to 4000 Hz. The mattresses proved tobe sound absorbing comparable to mineralwool of the same thickness.

Cushions used as soundabsorbing

baffles

Measured SpeechIntelligibility values

using a smallloudspeaker sound

source

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Noise and vibration control inmultiplex cinemas

Junction box treatment:- as walltreatment

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Floating floor construction method

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Acoustic Cinema Neighboring auditoriums should be separated withpartition walls of approximately 85 db 18-20000 hz.

Acoustic deflecting surfaces on the ceiling with lowacoustic delay difference time.The reverberation time can increase with increasingroom volume and decrease from 0.8-0.2 secs from

low to high frequency.The rear wall behind the last row of seats should besound absorbent to prevent echo.

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Acoustic Treatment Done InAuditorium ACOUSTIC TREATMENT

A double layered gypsum board(2 x 15 mm thick) for false ceiling with100 mm thick fiber glass(32 kg/cum) .For walls fiber glass(32 kg/cum) of 100 mm thickness and black tissuefacing is supported in 100 mm GI stud frame work@610mm c/c withchicken mesh on both sides of insulation with air gap.

The side walls have been treated with 100 mm thick fiber glass (12kg/cum ) supported in 100 mm GI stud framework @ 610 mm c\c withchicken mesh for air gap and finally fixing 2 layers of gypsum board ( 15mm thick ) over GI frame work.The side walls above 2400 mm have been treated with 50 mm thickfiber glass (32 kg\cum) with black tissue facing supported in 48 mm GIstud framing @ 610 mm c\c with chicken wire mesh.

Fix 100 mm thick acoustic panels comprising 100 mm thick fiber glass (80 kg/cum ) wrapped with acoustically transparent fabric supported in100 mm GI stud framework with one side chicken wire mesh & otherside finished with perforated GI sheet. The panel is to be mounted onsingle layer of 15 mm thick gypsum board fixed on the wall with GIsection.

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Slap Echoes and reverbation

When surround sound evolved, the Academy directive statedthat the story must not be dependant on the added soundtracks. An audience attending a mono only cinema must be able tounderstand the story. Because excessive slap echoes andreverberation destroy intelligibility and stereo imaging, the

added sound tracks have limited effect. Many films are produced with dialogue from the centerspeaker only, left-right and surrounds minimally used similar tothe percentages shown in the below pic.

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A simple hand clap at the front of thecinema will reveal the slap echoesacross the walls floor and ceiling

which evolve into reverberation, andwill be clearly heard. As a general rule the first earlyreflections within 30 milli-seconds areheard as being part of the directsound. Whereas after 30 milli-seconds the later slap echoes andreverberation are heard as beingfrom the room.

But most often the sound from thespeakers will be continuous andconstantly generating slap echoesand reverberation throughout the

cinema room, which becomesincluded within the following

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COCONUT HUSK,MATTING, BATTENING

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