The roof of a movie theatre and a conference hall is coverd
In Concert Halls, music or other sounds are produced on the stage and must be carried through the air to people in the crowd. Some of these sound waves go directly to the people in the crowd, without bouncing off of anything first. However, other sound waves from the stage first go to areas like walls and ceilings, then the sound either bounces off or is absorbed. When sound waves bounce off of a surface, the new direction they travel is related to the angle they strike the surface.
The roof of a conference hall and a movie theater is curved. It is done to enable uninterrupted reflection of sound from all angles. The sound that is produced will reflect from all parts of the roof and after reflection reaches all corners of the hall uniformly.