Explain giving scientific reasons.

A. The roof of a movie theatre and a conference hall is curved.

B. The intensity of reverberation is higher in a closed and empty house.

C. We cannot hear the echo produced in a classroom

A. Reason: Sound waves get reflected from the roof multiple times. This causes a single sound to be heard continuously. This is called reverberation. The time between successive reflections of a particular sound wave reaching us becomes smaller and the reflected sounds get mixed up and produce a continuous sound of increased loudness which cannot be deciphered clearly. To avoid this phenomenon, the roof of a movie theatre and conference hall is curved.

B. Reason: In a closed room, there are many objects or obstructions acting as sound absorbers. So the amount of sound getting reflected is very less. But in case of an empty room there are no obstructions. So, sound gets reflected multiple times leading to greater intensity of reverberation.

C. Reason: The dimensions of a classroom usually do not exceed 17.2m. If the dimensions are greater than 17.2m , echo is produced. So echo is not produced in a classroom.