| 摘要 |
PURPOSE:To make a cordless telephone system hand-free, and to prevent the generation of howling by providing an active filter for setting peaks of frequency characteristics of a bone conduction microphone and a speaker for constituting the bone conduction earphone microphone so as not to be overlapped with each other. CONSTITUTION:This system is provided with the bone conduction earphone microphone integrated with a bone conduction microphone 16 and speaker 13, and active filters 19, 20 for setting peaks of frequency characteristics of the bone conduction microphone 16 and the speaker 16 so as not to be overlapped with each other. That is, an acoustic converting circuit 12 is constituted of the bone conduction microphone 16 for inputting a voice signal through the active filter 20, and the speaker 13 for reproducing a signal received through the active filter 19. The speaker 13 can be possessed with the frequency characteristics for suppressing a high frequency, and the microphone 16 can be possessed with the frequency characteristic for suppressing a low frequency. That is, since the frequencies are deviated respectively through the active filters 19, 20, the sum of the frequency characteristics of the speaker 13 and the microphone 16 is made uniform. |
