Answers

2015-05-10T20:41:57+05:30
Echo is caused by the reflection of sound from a large reflecting surface or obstacle.
An echo can be heard only if there's a minimum distance of 17.2 meters between the obstacle and the listener. An echo is mostly clear and distinct.

How ever, a Reverberation is caused by caused by the over lapping of many echos. Reverberation is the term used for persistance of sound due to super posing of many echos. A reverberation is often muffled and unclear.
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2015-05-11T14:12:51+05:30
Echo -reflection of sound happened >0.1sec                                                       reverberation-reflection of sound happened < 0.1sec                 
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