Question

the roof of a movie theatre and a conference hall is curved

Answer 1

The ceilings of concert halls, conference halls and cinema halls are made curved so that sound, after reflection from the ceiling , reaches all the parts of the hall.

Answer 2

$\sf\blue\bigstar$ Sound waves get reflected from the walls and roof of a room multiple times. This causes a single sound to be heard not once but continuously. This is called reverberation.

$\sf\blue\bigstar$ Due to reverberation some auditoriums or some particular seats in an auditorium have inferior sound reception which can be compensated with curtains.

$\sf\blue\bigstar$ Ceilings of these halls are made curved so that sound after reflecting from the ceiling, reaches all parts of the hall and the quantity of sound improves.