TELEPHONE SET

PURPOSE:To attain always clear talking by keeping always the sound pressure level difference between an incoming voice signal and a side tone constant and giving the result to a receiver. CONSTITUTION:A transmission voice signal (f) inputted from a transmitter 10 is given to a telephone circuit 30, outputted from a subscriber line 50, a side tone (b) is outputted from the telephone circuit 30 at the same time and inputted to a difference detection circuit 41. The difference detection circuit 41 detects the sound pressure level difference between the incoming voice signal (a) and the side tone (b) inputted from the subscriber line 50 and outputted from the circuit 30 and gives an output it to an amplifier circuit 42 as a sound pressure level difference signal (c). The amplifier circuit 42 based on the sound pressure level difference signal (c) amplifies the incoming voice signal (a) to a prescribed sound pressure level and outputs an amplification incoming voice signal (d) to a voice mixing circuit 43. The voice mixing circuit 43 mixes the side tone (b) and the amplified incoming voice signal (d) and gives an output to the receiver 20 as the received voice signal (e). Thus, communication being always clear is attained.