(a) Reverberation: The repeated reflection of sound waves that results in the persistence of sound for some time is called reverberation.
In a big hall or an auditorium, along reverberation is highly undesirable. It makes the sound distorted, blur red and confusing.
Methods for reducing reverberation:
1. To reduce the undesirable effects due to reverberation, roof and walls of the auditorium are generally covered with sound-absorbent materials like compressed fibreboard, rough plaster or draperies.
2. The seat materials are also selected, having sound absorbing properties, Carpets are used to absorb the sound. Curtains are used on doors and windows to absorb the sound.
(b) Reflection of sound leads to the formation of echo. When a sound is repeatedly reflected from a number of obstacles, such as two parallel distant buildings or hills, more than one echo can be heard.