| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a simultaneous two-way speech device using an ear- microphone where a problem of howling in the case of transmission and reception is solved, a reception sound volume is sufficiently increased and then the device is used at a noisy place or the like. SOLUTION: A transmission/reception sound volume adjustment circuit 10 is interposed between an ear-microphone 1 having a microphone 4 and a speaker 5 and a communication equipment such as a PHS 20, and the circuit 10 is provided with a transmission reception changeover means 16, means 17, 19 attenuating a received voice signal for transmission and cutting-off a high frequency signal in the received voice signal and a means 15 attenuating the transmission voice signal for reception. Preferably, the circuit 10 includes a means 14 cutting off an energy in the vicinity of a resonance point of the microphone 4 and a means 12 detecting the energy around a 1st formant of the voice so that the changeover between transmission and reception is not caused by external noise or the like.</p> |
