Question

the roof of movie theatre and conference hall is curved

Answer 1

The  roof of the movie theater as well as the conference hall are intentionally made curved . This is done so that the sound produced can be reflect  from the roof parts and  also from the walls so that the sound produced can be reached in all part of the theater or the conference hall. This helps the sound to reach to the every person in the hall. This is purely made on the principle of reflection of the sound. These curves can result in the  process of reverberation .

Answer 2

hey here is your answer
ceilings of concert halls and cinema halls are curved to avoid undesirable reverberation.Otherwise, pitch of music will not be heard distinctly.
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