PURPOSE: To prevent voice control caused by erroneous detection by a method wherein a reference level for judgment of a voice input level is increased, or the voice signal in the sound information is decreased, by detecting the increasing tendency of a noise level in a vehicle.
CONSTITUTION: The sound information including voice control and noise is inputted to the microphone 1 which is connected with the comparator unit 3 via the rectifier 2. The comparator unit 3 is composed of the smoothing circuit 31 having large time constant, the smoothing circuit 32 having small time constant and the comparator 33 which compares the reference level signal (threshold value) with the voice signal. The comparator 33 is connected to the judgment unit 4 which judges the voice control input. The power-window switch 5 is connected via the motor M to the level detecting circuit 6 which detects the open or closed condition of the window. Said circuit 6 is connected to the analogue switch 71 of the threshold variable circuit 7 which is provided the adding unit 72 in which the output from the switch 71 is added to the output from said smoothing circuit 31. The adding unit 72 is connected to the comparator 33. The judgement unit 4 is connected to the relay 8 located between the power supply B and the switch 5.
NOUSO KAZUNORI
FUTAMI TOORU
