Mix-minus

Mix-minus is often used to prevent echoes or feedback in broadcast or sound reinforcement systems.

A common situation in which a mix-minus is used is when a telephone hybrid is connected to a console, usually at a radio station.

Because of the delay that is introduced in most means of transmission (including satellite feeds and audio over IP connections), the remote subject's voice has to be removed from their earpiece.

[1] Another common example is in the field of sound reinforcement, when people need to hear a full mix except their own microphone.

Legislative bodies of government may use a large mix-minus system, for instance houses of parliament or congressional groups that have a small loudspeaker and a microphone at each seat.