| 摘要 |
PURPOSE:To prevent abnormal setting against an impulsive noise by integrating the noise at each prescribed time and setting the amplification factor of a voice signal proportional to the integrated value just before the reception thereby attaining a proper reception sound volume in response to the noise. CONSTITUTION:A speaker 1 acts as a microphone at transmission and a speaker at reception by the changeover of a switch S and a transmission/reception section 2 exchanges a signal with other interphone. A noise detection section 4 integrates the noise at each prescribed time T and sets the amplification factor of a sound volume adjusting section 3 in proportion to the integration value just before the reception. Then proper reception sound volume is obtained automatically at all times even at a location where noise is changed like a bath room. Further, since a value integrating the noise is used, abnormal setting of the amplification factor is prevented even with an impulsive noise. |
