Echoes vs. Reverberation

Echoes and Reverberations

• ECHO
  An echo is the perceived reflection of sound from a surface.
  The fraction of sound level that is reflected is known as the reflections coefficient.
  0 <= α <= 1
• The time difference between the echo and the direct sound depends on the distances travelled and the speed of sound.
• The smallest distance for sound to travel to be described as an echo is 33m. However because it is an echo the sound has to travel to eg. a wall and bounce back therefore travelling 17m each way.
• The difference must be greater than about 100ms to be perceived as an echo.

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• REVERBERATION
  The persistence of a sound after its source has stopped, caused by multiple reflection of the sound within a closed space.
• The reverberant character of a room is due to the accumulated reflections from all the surfaces (walls, floors,ceiling and other objects) adding to the direct sound.
• Multiple level reflections occur as well as single ones.

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