Burns & Lobato, P.C.
Speech circuit controlling sidetone signal by background noise level
 A speech circuit is disclosed which solves the serious problem of the degradation of the articulation of received speech voice in conventional circuits and permits pleasant communications at places where the background noise level is high. The circuit has a construction in which an input signal from a microphone is attenuated in correspondence to the background noise level to form a sidetone signal and a received speech signal from a speech channel is amplified in correspondence to the background noise level to form a new received speech signal. 
Kokusai Electric Co., Ltd.
H H
H04M H04M
inventional inventional
Osamu
Watanabe