| 摘要 |
<p>A system for control of speech direction in duplex telephone circuits (e.g. hands-free telephone), derives a switching control signal proportional to both the immediate transmit-channel signal value and a Regulating Value which is the ratio of the Receive-Channel Signal to the TransmitChannel Signal under no-local-sound-source condition. Thus the Regulating Value is proportional to the local acoustic feedaround (Overhearing) signal between local loudspeaker to microphone. The Regulating Value responds to faster variations(caused by speech) to cause direction-switching, but merely compensates for slower variations (caused by movement of people or microphone in the local room). Switching(Breakthrough) of the microphone to On and the loudspeaker to Off also depends on the magnitude of the closed-channel(non-corrected) microphone signal exceeding that of the open channel.</p> |
