PURPOSE: To reduce the degree of sound coupling between a microphone and a speaker and to improve the quality of speech characteristic in the titled telephone set using a voice switching circuit, by using a differential output of the microphones in the same group as a microphone output.
CONSTITUTION: This telephone set has pairs of unidirectional microphones 24 and 24' and 26 and 26' which are arranged so as to opposit reversely their assigned characteristics, and microphones 24, 24' and 26, 26' are arranged so as to coinsides the perpendicular bisector Z of line segments X and Y connecting microphones of the same groups with the axis of a speaker 22, and outputs differential outputs of microphones 24 and 24' and 26 and 26' of each group as the microphone output. Therefore, the receiving signal entering into microphones 24 and 24' and 26 and 26' from the speaker 26 is reduced to almost 0, because microphones 24 and 24' and 26 and 26' of each group offset each other in the same group by differential amplifiers 31 and 32.
| JPH0723098 | TELEPHONE SET |
| WO/2016/109045 | MOBILE DEVICE IN-VEHICLE LOCALIZATION USING INERTIAL SENSORS |
| WO/2000/070390 | SPECTACLES |
SUDOU YOUZOU
YOKOYAMA TOORU
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