PURPOSE: To eliminate the unpleasant feeling of users by stopping the output to a man-machine when the level of a subtracted voice signal is higher than that of an unsubtracted voice signal in terms of the voice of its own terminal.
CONSTITUTION: A subtraction processing part 14 subtracts the voice signal (supplied in past) received from a delay processing part 21 from the voice signal received from a transducer 13 and then transmits the signal obtained from this subtraction to a voice decoding part 17, a level comparing part 50 and an addition processing part 15 respectively. The part 50 compares the voice signal received from the transcoder 13 with the voice signal received from the part 14 in terms of these signal levels. If the level of the latter signal is higher than the former one, the part 17 is instructed to stop transmission of signals to a voice output part 18. It is clear that the input voice signal is not normal if the level of the processed voice signal is higher than that of the unprocessed voice signal. Thus this abnormal signal is not transmitted to a man-machine and therefore no impact sound is produced from the man-machine.
MATSUI HIROYUKI
IRISHIMA TSUTOMU
