| 摘要 |
PROBLEM TO BE SOLVED: To provide an interphone system for multiple dwelling houses with which howling is automatically controlled by integrating an automatic level control function into the function of a public entrance machine. SOLUTION: This intercom system is composed of a public entrance machine 30 provided with an operating part 33, an audio circuit 35 and a control part 31, plural living room base units 40 having living room numbers, a janitor room base unit 20 and a controller 10 for controlling speech paths and control signals with the janitor room base unit 20, the living room base units 40 and the public entrance machine 30. The audio circuit 35 is provided with a reception level receiving circuit 358 for detecting a reception signal level to be outputted to the speaker of the audio circuit 35 when an operation is performed from the operating part 33 in order to control howling in the public entrance machine 30 and a voice reception level variable circuit 357 for controlling the voice level.
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