Sidetone

Sidetone is audible feedback to someone speaking or otherwise producing sound as an indication of active transmission. Sidetone is introduced by some communications circuits and anti-sidetone circuitry is used to control its level.

Sidetone is expected behavior for telephone systems. Absence of sidetone can cause users to believe the call has been dropped or cause them to speak loudly. Too much sidetone can cause users to speak softly.