Telephone with automatic pause responsive, noise reduction muting and method

摘要

A telephone with an automatic muting circuit that mutes the microphone in response to detection of speaking pauses of the local user to reduce noise due to acoustical feedback that are detected by comparing the waveforms from the microphone and the audio speaker after being amplified by amplifiers with automatic gain control circuits to the same level with speech subtractor. During pauses when the signals compared are substantially the same, then automatic muting circuit is activated by the speech subtractor to mute the microphone but when the local user speaks into the microphone the subtraction of the waveforms does not yield a null result and the microphone is unmuted.