Rewa, Pallavi

8/13/2019 Rewa, Pallavi

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ACOUSTICAL MATERIAL

SUBMITTED BY:

Rewa Marathe

Pallavi Chitnis


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Need for acoustical treatments goes back to Greek,since when they started using amphitheatres. Back inthose days these were achieved using brass vesselsfilled with water or other methods of similar kind.Now we have come a far way from those water filledbrass vessels. Today we use latest technology and

material to achieve desired acoustical effect. They are used for treating rooms with special

audibility requirements like auditoriums, movietheatres, amphitheatres, seminar halls, conferencerooms, recording rooms, etc.

Classification of acoustical materials: Sound absorbent

Sound reflecting


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Various kinds of materials are available in market. They

are listed below:

ACOUSTICAL PLASTER

ACOUSTICAL TILES

COMPRESSED WOOD PARTICAL BOARD

MINERAL WOOL

STRAW BOARD

PERFORATED PLYWOOD

FIBRE BOARD

WOOD WOOL BOARD

FIBRE GLASS

CORK BOARD/TILES

ROCK WOOL AND GLASS WOOL

GYPSUM BOARDS

THERMOCOL AND CORK

CARPETS AND CURTAINS


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ACOUSTICAL EFFICIENCY It most important factor and is

expressed as absorption coefficient of any material..

MAINTENANCE After insulation, maintenance plays a very

important role. Material selected should have clean and

presentable appearance, capable of being washed and

renovated if required.

VERMIN AND ROT PROOF- Acoustical Material are applied

to serve for long period and therefore they must be free

from these defects.

RESISTANCE TO PHYSICAL IMPACT- they should posses

adequate abrasive strength snd should not be affectedby physical contact.

RESISTANCE TO MOISTURE- they should have sufficient

resistance to mositure, but they should not be used in

damp conditions.


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HEAT INSULATION- MATERIAL CHOICE CAN CUT DOWN AIR-

CONDITIONING AND WINTER HEATING TO QUITE AN

EXTENT.WHILE SELECTION OF A MATERIAL IT SHOULD BECONSIDERED WHETHER IT IS TO BE APPLIED ON CEILINGS

OR WALLS.

INCOMBUSTIBILITY-ACOUSTICAL MATERIAL SHOULD BE

RESISTANT TO FIRE . FLAME RETARDANTS SHOULD BE

RENDERED IN THE MATERIAL WHILE ITS MANUFACTURINGPROCESS,TO PROVIDE ADDITIONAL HEAT INSULATION

PROPERTY TO THE MATERIAL

WEIGHT-LIGHT ACOUSTICAL MATERIAL ARE MORE SAFE TO

USE,AS IT ADHERSE PROPERLY TO THE SURFACE TO BE

TREATED AND CAN ALSO SUSPEND EASILY. AESTHETIC APPEARANCE- THOUGH THIS PROPERTY IS NOT

REALLY VERY IMPORTANT,BUT IT IS PREFERRED IF GOOD

FINISHED SURFACE IS ACHIEVED, WITH ITS ACTUAL PURPOSE

OF INSTALLATION


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SOFTMATERIALS- MATERIALSHAVINGSUFFICIENTPOROSITYANDGOODABSORBINGPOWER; LIKEHAIRFELT,ASBESTOS,ROCKWOOL,GLASS

SILK,ETC.FALLUNDERTHISCATEGORY.

SEMI-HARDMATERIALS-MATERIALSABLETOWITHSTANDROUGH

HANDLINGLIKECANEFIBRE,MINERALWOOLBOARDSANDTILESFALL

UNDERTHISCATEGORY.ACOUSTICALPLASTERSARESEMIHARDMATERIALS, WHICHCANBEAPPLIEDLIKEORDINARYPLASTER,THOUGH

REQUIRESKILLEDLABOURSFORITSAPPLICATION.

HARDMATERIALS- HARDPOROUSMATERIALS,MADEPOROUSDURING

THEIRPROCESSOFMANUFACTURING,LIKEPRFORATEDPANELS,POROUS

TILES,ETC.FALLUNDERTHISCATEGORY.


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ACOUSTICAL PLASTERS AND SPRAYED ON MATERIALS.

PREFABRICATED BOARDS OR TILES.

COMPOSITE OR ASSEMBELED UNITS.


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Correct techniques and proper job conditions should

followed for application

No installation should be done when the building is

recessively cold, damp, hot or dry.

All plastering concrete and terrazzo work includinggrinding should be completed and then made dry.

All doors and windows should be in place ad glazed.

Poured or precast concrete and gypsum or similar roof

decks should be thoroughly dry.

Form oil should be removed before application.

All the precautions should be discussed with the

acoustical.


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Suspended ceilings are used for many purposes including

acoustical treatments in form of tiles and sheets.

Suspended acoustical ceilings serve to provide sound

absorption and the most useful surface in a room. They

help in reducing reverberant sound intensity within a

room.

Sound absorbing ceilings available in the market today.

Human activity in offices and large publics paces generates

noise resulting in reduced work efficiency. Acoustical

(sound absorbing) ceiling systems help in reducing build-up

of reverberant noise because

of their excellent sound absorbing properties. This leads to

a better

Working environment and reduced annoyance due to high

noise levels.

In selecting a suspended ceiling ,the designer needs to

weigh the and performance requirements.


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Ceilings systems are available in gypsum, coated steel and

coated aluminum. They available in a variety of designs

including lineal ceilings, I-in or lay-in tile and plank

ceilings and C-grid (band raster) ceilings. Metal ceiling as

remanufacture in d aluminum and steel with coil coated

powder coated finishes. All metal ceilings are available in

a perforated version for sound absorption, and are

designed to integrate the standard lighting fixtures air

diffusers and partitions .


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Sound absorption

The sound absorbing efficiency of material is designated byits sound

Absorption coefficient (a). This is usually measure and

reported in octave bands over the frequency range of 125-

4000Hz, together with the Noise Reduction Coefficient

(NRC), which is the average of the sound absorptioncoefficient 250,500,1000and 2000Hz. This enables

calculation of noise reduction or reverberation time.

The increasing use of hard finishes and stone/tile finishes

in offices requires the use of highly sound absorbent

ceilings. offer NRC values of 0.75 up to 1.05 for differentceiling types.


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Traditionally, whenever sound absorption is required,

perforated metal ceiling panels are backed with a sound

absorbing layer of mineral wool or fiber glass. The use of a

fibrous sound absorbing medium always has other draw back is.

These include the difficulty in working with the fibrous

materials because of skin irritation and the problem of fibers

letting loose in to the air stream in an air-conditioned

environment. This ceiling range comprises perforated panels

with an acoustic non woven factory applied to the rear of the

panels. Due to the controlled sound impedance of this

perforated panel, and with a backing air space (ceiling

plenum)the, provides excellent sound absorption properties

without the use of any fibrous material behind the perforated

panel.


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SOUNDTRANSMISSION LOSS

Sound transmission loss is a measurement of soundinsulation between one room and an other. Onemanufacture provide sound

Transmission loss values for ceiling tiles.This information is

of doubtful utility because ceiling tiles are supported ongrids and

Have penetration through them to accommodal tieghtfittings and air

conditioning diffusers The overall sound transmission lossof such a composite ceiling will be 10-20dB lower than the

transmission loss of the ceiling panel ort ile alone.Whendesigning for soundi nsulation between rooms, thepartitionseparating the rooms is of major concern. Toprevent flanking sound transmission through thesuspended ceiling,it is important that partitions do notStopat the ceiling,but are extendedRight upto the roofslababove. sound insulationBetween adjacentspaces.


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Acoustic Wedges: To achievefree-field conditions within an

acoustic test environment for the

measurement of radiated sound

power and directivity, the testing

area must be free fromreverberation, feedback and

resonance throughout the audible

frequency spectrum.

Adhesive

Baffles: Baffles are used formost any interior space in need

of quality acoustical control.
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Barriers/Composites/Foam

Viscoelastic-damping

Compound, a high-performance

viscoelastic-damping compound,

decreases the sound traveing to

adjacent rooms.

Ceiling Tiles pinta's ceiling tiles

add texture, style and color to

any interior while solving a wide

array of acoustical issues
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Ceiling Tile Noise

Barrier CompositeCeiling Tile Noise Barrier

Composite improves the

transmission loss abilityof existing acoustic

ceiling tiles.

Ceiling Grid System

System is offered in

colors that complementthe Hypalon coating or

natural finish ceiling tiles

as well as our metal

ceiling tiles.
http://www.illbruck-sonex.com/products_CeilingGridSystem.phphttp://www.pinta-acoustic.com/UserFiles/CEILING_TILE_NOISE_BARRIER_COMPOSITE_3_08(1).pdf


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Noise Control Curtainscurtain products to produce an

effective and economical method of

noise reduction for a wide variety of

industrial applications.

Wall Panels pinta offers a variety of

wall panels to meet all your acoustic

challenges.

Pipe Lagging PROSPEC Pipe Lagging

combines non-reinforced barrier witha thick foam decoupler to reduce

the noise created by vibrating pipes.
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Building bye laws by MP CINEMA ACT, 1972

construction:

No cinema shall be constructed underneath or on top

of any other building.

No open space shall be allowed under the floor ofauditorium.

Height of tiers:

Where the first tier or balcony extends over any part

of auditorium and such tier or balcony shall not be less

than 10 feet.


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Entrance and exit:

Cinema shall have a road frontage on the public

thoroughfare upon which the site of such cinema

abuts, and in such frontage there shall be suitable

means of entrance and exits for public . In addition

entrances and exits shall be reserved for service in

case of emergency opening on two separate and

distinct passages shall not be less than 5 feet width.

Two separate exits not opening on the same

thoroughfare of public passage shall be provided from

stage and from auditorium floor. Each of such exits

shall not be less than 5 which between the leaves of

the door when open.


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Seating : No part of auditorium shall provide accommodation

exclusive of passage, as a higher scale than 20 persons

per100 square feet.

All seats in the hall shall be firmly secured to the floor.

Gangways : A clear passage or gangway shall be formed at the sides

and down the centre of the seating in every part of the

auditorium in such a manner that no seat shall be ten or

more feet distant from a passage.


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Doors: All doors for the use of public shall be at least 46 wide with

the clear.

All doors shall open outwards to lie finish with the outside ofthe wall.

Width of corridor No staircase, landing lobby, corridor or passage, not being an

internal passage, not an internal passage between rows ofseats, intended for use as exit shall be less than five feet wideand there shall be no recesses or projection in the wall.

Staircase: Treads should not be less than 11 inches wide and with risers of

not more than 6 inches high. No staircase shall have more thantwo flight of 15 steps without a turn.

Ventilation : The area of the window, door and ventilator opening shall not

be less than one fifth of the total floor area.


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Planning:

The following conditions must be taken care of whileplanning a theatre:

1. Every member of the audience should have anunobstructed view of the entire picture withoutvisual, physical, and picture distortion.

2. Resolution and luminance of the picture must besatisfactory.

3. The auditorium should be suitable for soundreproduction and should be distortion and

coloration free.

4. There should be a reasonable balance betweenscreen size , viewing condition, seating conditionand circulation requirement.


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The size and the position of the screen must

relate to the size and shape of the

auditorium.

The max. distance of seating from screen isrecommended as five times the width of the

screen.


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It shall be three times for the screen of 35mm projection.

It shall be 2.5 times for the screen of 70 mm projection.

The overall length of the rear seating should be 3 times

width of the screen, 2 times for 35 mm projection and 2.5

to 3 times for 70 mm projection. The first row of seats should notbe closer to the screen.

The angle formed with the horizontal by a line from the

top of the projected picture to eye of the viewer in the

front row seat, should not exceed 35o preferably 30o.

The distance of screen from the first row shall be 2/3 ofthe screen width.

The width of seat pattern should vary from 1 times the

widest projected picture at the row to 1.3 times at the

row farthest from the screen.


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The volume provided in the hall is such that each person is

provided a space for about 3.75 times to 4.5 cum per

person.

Ration of H: W: l is 1:2:3 for approximate 800- 1000.

The size depend upon the total seating capacity, shape ofauditorium depend upon the acoustical requirement.


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The rear wall may be straight or curved

The rear wall does not folow the line of

curvature of the last seating row

The difference in shape of auditorium thuslies in pattern of side wall. They may be

rectangular, parabolic and diverging for part

or full, surated and splayed.

Usually concave divergence is emploeyd nearthe stage with straight and rectangular sides

towards rear.


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The ceiling of auditorium for cinema is not

normally provided as a flat horizontal

surface, as this type of ceiling causes uneven

distribution of sound and creates flutter and

echoes. The ceilings are applicable for upto

400 people.

Splayed ceiling with splays rising towards

rear reinforces sound for the rear seats.

Ceilings are principally sound distribution

surface and need no sound absorbing

material if properly designed.


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The generally acceptable noise level inside the auditoriumfrom point of view of comfort , economy and otherpractical consideration shall be 30 to 40 db.

The recommended Rt is .35 to .55 seconds for 1500cum.

Acoustical conditions:

This depend on auditorium shape acoustical absorptioncharacteristics of surface and reverberation resulting fromthem.

Rectangular rooms with parallel floors and ceiling surfacesspecially if long and narrow give worst results.

The ideal is fan shaped auditorium which is also ideal forviewing conditions.

Decay conditions: The characteristics of decay curvature of cinema should be

such that with reflected sound waves is attenuated by not lessthan 15 db by comparison by direct sound.

For cinema theatre reflected sound path should not exceed thedirect path more than 15m.


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A multiplex with four Audis.

It has a capacity of 250 people in each audi.

Acoustical treatment has been done using tapestry, micron

wadding, gypboards, fibrecrete, and woodwool panels.

Treatment has been provided between the wall which iscommon between two Audis to avoid passage of sound

from one Audi to the other. This has been done by

providing cavity wall filled up with micron wadding an

alternative of glass wool.

The floor has been covered with black acoustical carpet.


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Sound source is situated is situated behind

the screen in form of three LCR speakers.

The first 3-4m of the side recieves max.

intensity of sound and thus is heavily treatedfor absorption. The rest is divided into three

equal parts and treated for reducing sound

intensity in direction from screen towards

the rear.

The ceiling is treated Gyp boards.


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Rewa, Pallavi

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