Reverberant Sound Field
A sound field made of reflected sounds in which the time average of the mean square sound pressure is everywhere the same and the flow of energy in all directions is equally probable. This requires an enclosed space with essentially no acoustic absorption, e.g., a reverberation chamber. Sometimes reverberation is confused with an echo but strictly an echo is a discrete repeat of a sound event.
Reverberant sound builds up and decays at a rate characterized by the reverberation time, which depends on the room volume and the absorption of all the surfaces in it.
Reverberation is most noticeable in very large places with many hard reflective surfaces which are at complex angles to one another, such as large churches.