Mumbai university > FE > SEM 1 > Applied Physics 1

Marks: 5M

Year: May 2014

Acoustic requirements of a good auditorium:-

• The sound waves from the source should be of an adequate intensity.

• The sound should spread everywhere inside the hall evenly and should be audible enough everywhere.

• The sound notes should be clear and distortions should be minimum.

• Undesired noise interfere with the sound from the source should be minimized.

• Sound distortion due to shape and size of an object present in the auditorium must be reduced.

• Proper reverberation time according to preferred values is also important.

Means to achieve:-

• The site for the auditorium must be selected carefully and noisy areas like near the railway tracks or airports must be avoided.

• Size of the auditorium must be optimum as small size would create irregular distribution of sound while large size will result into weaker intensity sound waves and larger reverberation time.

• Avoiding echoes and focusing of sound waves is important as they cause non uniform sound level within the room which is undesirable.

• In order to achieve this, we can make use of scatters, convex (non-focusing) surfaces on balcony fronts, sound absorption materials on concave surfaces and flat surfaces, carpets, and upholstered seats.

• The reflections from the rear walls and ceiling may cause disturbance, hence it must be reduced by using absorbents.

• Reverberation time can be controlled by proper use of absorbing materials, optimum number of audience, presence of optimum number of windows, etc.

• Railings or staircase or any regularly spaced objects will reflect the sound waves from the source and produce echoes in regular successions. This phenomenon is called Echelon effect. This can be reduced by covering such surfaces by a thick carpets or absorbents.