Some desirable controls for an artificial reverberator include 
The time to decay 60 dB ( ) is a classical objective parameter used as a measure of perceived reverberation time. Classically, was measured for the whole response. More recently , it has become more common to design for a given at more than one frequency, e.g., one for low frequencies, another for high frequencies, and interpolated values at intermediate frequencies. Perceptual studies indicate that reverberation time should be independently adjustable in at least three frequency bands .