The decaying residual signal that remains after a sound occurs, created by multiple reflections as the original sound wave bounces off walls, furniture, and other non absorptive barriers within a room or other acoustical environment. Reverberation contains the same frequency components as the sound being processed, but no discrete echoes. An average club has a natural reverberation time of about a half-second; many concert halls and auditoriums have a natural reverberation time of two seconds or more. A room with very little reverberation is called a dead room, which is the opposite of a live acoustic space which is very reflective. Reverberation is composed of early reflections and later reflections.
High-frequency sound waves have to cause the surrounding air molecules to vibrate quickly enough to pass the sound energy onwards, consequently high-frequency reflections die out faster than mid-frequency or bass reflections. Also, high-frequency sound is more readily absorbed by soft furnishings. Low-frequency sounds are only reflected by large and heavy objects, so there may be very little low-frequency reverberant sound. However, in larger rooms, there can be substantial bass build-up.
