PURPOSE: To obtain some mental effect while satisfying information transmitting function, by adding a voice processing circuit to the channel system of a telephone set, and processing voice signals so as to obtain voices which are different from original ones.

CONSTITUTION: A channel system 101 forms a voice signal transmitting route on the transmitting side, receiving side, or both transmitting and receiving sides of a telephone set. A voice processing circuit 102 processes voice signals of the channel system 101 and produces voices which are different from original ones. The voice signal transmitted through the channel 101 is transmitted to a partner or talker after it is changed by means of the processing circuit 102. Therefore, this telephone set can feed some mental effect to the partner or talker while satisfying its information transmitting function.