When sound is produced in an enclosed space multiple reflections build up and blend together creating reverberation or reverb. This is most noticeable when the sound stops but the reflections continue, decreasing in amplitude, until they can no longer be heard. The time it takes for the sound pressure level of the reverberation to decay 60 decibels is known as the reverberation time, or RT(60).
Large chambers, especially such as cathedrals, gymnasiums, indoor swimming pools, large caves, etc. are examples of spaces where the reverberation can clearly be heard. Reverberation can make it difficult to hear speech. If the reverberation from one syllable overlaps the next syllable it may make it impossible to hear. For instance, "cat", "cab", and "cap", will all sound the same. This loss of information makes reverb a useful tool in studios for "smoothing" sounds- a common application is on vocals to help generate the illusion of consistent pitch. Traditionally, this was achieved by recording sounds in reverberant chambers, but modern recording technology allows for analogue and digital processors which can simulate a wide range of spaces.
Different types of music tend to sound best with different reverberation times; during a live performance, classical music and choral music tend to require longer reverberation times than modern rock and popular music, for example. Pauline Oliveros, Stuart Dempster, and especially their group the Deep Listening Band have performed in very reverberant spaces, such as the Fort Warden Cistern, which has a reverberation of 45 seconds.
Reverberation times can differ depending on a frequency band, which is defined by the acoustic properties of the space. Short sample of reverberation effect ( file info) Clean signal, followed by different versions of reverberation (with longer and longer decay times). Problems listening to the file? See media help.
