Sound And Solid SurfaceSubmitted By:

Shubham Vasudev, 11627Sahil Atri, 11645

The interaction of sound with solid surface could well be taken as beginning of architectural acoustics.

Sound waves under goes three type of fundamental interactions upon interaction with solid surface,

Reflection, Absorption, Transmission.

Reflection is done by two type surfaces:

Finite surface Infinite surface (sound absorption coefficient = 0)

Reflection :

These are the surfaces where when the sound waves collides it makes the source image on the opposite side of the surface.

Infinite Surface :

These are Surfaces of limited dim. and these surfaces are used in concert halls, where panels are frequently suspended as clouds over the orchestra and whole roofing

Finite surfaces:

Sound absorption :In sound absorption it is the property of the material which turn The sound energy into other forms of energy – e.g. thermal energyOr kinetic energy. (sound absorption coefficient = 1)

Types of absorbers :

Porous absorbers,

Panel absorbers,

Air motion induced by sound wave occur between the particles.

Due to movement through narrow constrictions there is huge loss of momentum into heat energy.

Porous absorbers :

Every solid substance absorb sound energy due to its mass reactance, more is the mass more will be the sound absorption.

Panel absorbers: in panel Absorbers partition is done By only a single panel of sound Absorbing material. Air backed panel absorbers: In this panel absorbers are followed by air gap and wall

Panel absorbers :

Adding sound-absorbing materials to a space usually becomes an interior design issue .

Absorptive materials are often covered with acoustically transparent surfaces such as fabric, perforated metal and spaced wood slats.

These surfaces allow the sound energy to pass through and be absorbed by the material located behind.

Wood slat panel absorbers :

Perforated metal absorbers :

Suspended baffles absorbers:

Open-cell foam panels are effective sound absorbers because they have increased surface area due to the contoured surface of the foam.

Sound diffusion :

In sound diffusion sound waves are partiallyAbsorbed and smaller wavelength waves are reflected. (sound absorption coefficient = between0 & 1)

More the mass of the wall, more is the sound transmission loss.

increasing the thickness and isolating the sides of wall, with the help of air cavity between the wall panels.

Principles of sound diffusion :

Sound diffusion in walls :

The STC rating of a wall, floor or ceiling is determinedby the components of the construction and how they are assembled (Sound Transmission Class)

plenum barrier is installed the operablewall, extending from the top of the wall to the structure underside of thestructure This plenumbarrier is required in order that the sound insulation value of the wall is maintained, and notshort-circuited through sound travelling over the top of the partition.

Accordion-type operable wall

Panel-type operable wall

Panel operable walls provide better sound insulation than accordion partitions because theyare heavier and their perimeter seals are more effective

Floor and ceiling assemblies perform two acoustical functions. Like walls, they provide acoustical separation between adjacent spaces

they alsoreduce the sound of footfalls and otherimpact from upper floor

Sound diffusion in Floor

Wood framed floor and ceiling

Thank you!