The reverberation time of an enclosed space, for a given frequency band, corresponds to the time interval required for the sound pressure level in that band, after the cessation of sound energy emission, to decrease by 60 dB. The value of the reverberation time depends on the frequency, the sound absorption of the materials that make up the exposed environment (coverings or defining elements of the enclosure), the objects in the enclosure, and the volume of the enclosure. The following figure illustrates this parameter.