PURPOSE: To improve S/N by common-mode rejecting voice signals outputted from a second microphone from the signals outputted from a first microphone, and outputting the obtained signals as transmitting signals.

CONSTITUTION: Impulsive noise components included in the transmitting voice signals outputted from the first microphone 3 and the impulsive noise components outputted form the second microphone 4 are almost at the same level and phase, because the first microphone 3 and the second microphone 4 are provided almost at the same position towards a switch 6. Thus, the impulsive noise components included in the transmitting voice signals outputted from the first microphone 3 are canceled by the impulsive noise components outputted from the second microphone 4. As the result, the transmitting voice signals whose impulsive noise components are reduced can be outputted. Thus, the S/N can be improved.