Have you ever wondered why is an echo not produced in a Cinema Theatre with huge speakers making loud sounds but a low noise in an empty room echoes?? Well u have the answer right here in a simple manner. An echo is formed as a result of reflection of the original sound which returns to the listener. You might have experienced Echo in an EMPTY ROOM but no echo is produced after the room is occupied. To avoid echo from being produced the echo has to be absorbed. Echo in a cinema theatre is absorbed by the WALLS of the theatre. So next time when you go for watching a movie, notice the WALLS of the Theatre. They are not plain. The walls are corrugated or shaped to form tiny holes or empty spaces to ABSORB the ECHO. Modern Theatre's have ABSORBENT materials sticked to the walls of the theatre.
This is why you dont hear an echo in a theatre with speakers shouting loud music.Echo cant be avoided but it can be absorbed effectively so that it cant be heard
