| 摘要 |
PROBLEM TO BE SOLVED: To enhance crime prevention and privacy protection by preventing indoor sound from being heard more than required by a partner's telephone conversation terminal even in a high echo place like a bathroom. SOLUTION: A noise generating section 40 is provided between a line output amplifier G2 and a two line/four line conversion circuit 3 in a signal path on the transmission side. The noise generating section 40 generates noise, e.g. so-called white noise, in the signal path on the transmission side. Since a bathroom has a narrow space as compared with a living room and echo is large, sound in the bathroom is possibly heard more than required by a partner's telephone conversation terminal but since noise generated from the noise generating section 40 is sent through the transmission side signal path to the partner's telephone conversation terminal, indoor sound is not heard more than required by the partner's telephone conversation terminal even in a high echo place like a bathroom, and thereby crime prevention and privacy protection can be enhanced. COPYRIGHT: (C)2006,JPO&NCIPI
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