(1) In stereophonic reproduction of music, depth refers to the perceived relative distance between the listener and the various instruments in the sonic image.
(2) In a digital delay or flanger, a parameter which modulates the length of delay around the specified delay time. Because this happens in real-time, the pitch of the input signal is varied, causing the output signal to have an apparent vibrato effect. The speed of this vibrato is set by a rate control.