Question

The walls and ceiling of an auditorium are covered with fibrous materials to
A. Make the auditorium fireproof
B. Absorb sound and prevent echoes
C. Give an ethnic look to the auditorium
D. To prevent leakage of water from the roof

Answer 1

Hint: Reverberation is the occurrence of the reflection of sound waves from the surfaces in an enclosure like an auditorium. The created sound gets reflected many times by different items in space. The reflected waves can result in constructive and destructive interference phenomena at different places in the auditorium.

Complete step-by-step solution:
A reverberation, or reverb, is a phenomenon, which is created when a sound or signal is reflected causing numerous reflections to build up and then decay as the sound is absorbed by the surfaces of objects lying in the space, which can include furniture, people, and air. Reverberation is defined as the collection of reflected sounds from the surfaces in an enclosure like an auditorium.
We know that a soft, porous, and fibrous material is a good absorber of sound, so it can be used to cover the walls and ceiling of an auditorium to absorb the sound.
In case the walls and ceilings of the auditorium are not covered with a fibrous material, sound waves after getting reflected from the walls and ceiling, and producing echoes, would interfere and due to this at some places in the auditorium, the sound will not be heard, where destructive interference would take place, and at some places, the intensity of the sound will be very large, where constructive interference would take place.
The walls and ceiling of an auditorium are covered with fibrous materials to absorb sound and prevent echoes.
Hence, the correct option is B.

Note: The roof and the walls of an auditorium or cinema hall are generally covered with sound-absorbent materials like draperies or compressed fiberboard to reduce the effect of reverberation. These materials reduce the formation of echoes by absorbing the sound waves.