Question

Why is the ceiling and wall behind the stage of good conference halls or concerts halls made curved?
A. it looks good
B. construction is efficient
C. to reflect sound in a specific direction
D. it absorbs sound effectively.

Answer 1

Hint: If the audience present in the concert hall wants to fully enjoy the concert then all the sound waves from the stage must reach the audience. If the walls and the ceiling are flat that this is not achieved. If the walls are flat, the sound that is going away from the audience will reach the audience.

Complete step by step answer:
Sound is a wave that is produced due the vibrations of air molecules. Since sound is wave, it can travel through different mediums.

When a wave passes from one medium to another medium, it is partially absorbed, partially reflected back at a specific angle and the rest transmitted through the medium. This rate of absorption, reflection and transmission depends on the material (medium) of the body on which the wave is incident.
There exists material that are good reflectors of sound and there exists material that are good absorbers of sound.

In a concert hall, we need the sound from the stage to reach every part of the hall. Some of the sound from the stage reaches directly to the audience sitting in front. However, the rest of the sound will hit the ceiling or the walls first.

The sound is reflected from the ceiling and walls at an angle. The sound should reflect at an angle such that the sound reaches the audience (towards the centre of the hall) and not hit a wall again.

If the walls and ceiling are flat, we may not achieve this purpose at full efficiency. Therefore, the walls and the ceiling are made curved because curved surfaces help in converging the sound waves. It is the same as a concave mirror reflecting and converging the rays of light at a point.

When the sound wave bounces on the wall and returns again, the repeated sound is called an echo. Therefore, we even have echoes in the concert, which make the music better.

This is the reason why the walls and the ceiling of a concert hall are made curved, i.e. to reflect the sound in a specific direction.
Hence, the correct option is C.

Note:
Note that along the surfaces of the ceiling and the walls being curved, the material of the ceiling and the walls must be good reflectors of sound. Otherwise, most of the sound will be absorbed by the walls and the ceiling.