Behaviour of Sound in enclosed spaces

Module-1




Behaviour of Sound
in enclosed spaces
Reflection
Diffusion
Diffraction
Absorption


Building Services IV (Acoustics And Noise Control); 15ARC 7.3
Faculty: Shanthala V, BMSCA

, Module-1
Reflection
•It is the return of a sound wave from
a surface
•If the surface dimension x is larger
than 4 times the wavelength ʎ of the
impinging sound wave, the angle of
incidence is equal to the angle of
reflection.




Building Services IV (Acoustics And Noise Control); 15ARC 7.3
Faculty: Shanthala V, BMSCA

, Module-1
Curved surfaces - focus
sound- causing hot spots or
echoes.

Curved rear walls in
auditoriums- cause
unsatisfactory perception of
sound due to uneven
distribution of sound energy

Concave surfaces are poor
distributors of sound energy
They should be avoided
where sound reflection is
desired.
Building Services IV (Acoustics And Noise Control); 15ARC 7.3
Faculty: Shanthala V, BMSCA

, Module-1

A shallow concave surface
may be satisfactory if the
focal point is outside the
enclosure.
Flat surfaces-
adequately large and
oriented properly
can effectively
distribute reflected
sound



Building Services IV (Acoustics And Noise Control); 15ARC 7.3
Faculty: Shanthala V, BMSCA