(1) In a multiple microphone set-up, the extent to which any one microphone is able to reject unwanted sounds intended to be picked up by other microphones. Separation is desirable if phase cancellation is to be avoided, and can be increased by careful microphone choice an placement. See directional microphone.
(2) The degree of isolation between signals flowing in two paths. Specified in decibels, indicating the level of a signal induced by one signal path in the other. See crosstalk.