| 摘要 |
PROBLEM TO BE SOLVED: To aurally inform that a vehicle speed exceeds a preset speed by putting a muting circuit in a mute operation state when a speed expressed by a vehicle speed pulse signal becomes the preset speed or more, and setting the sound volume of an audio from a loudspeaker small or to the wholly inaudible sound volume. SOLUTION: An on-vehicle audio system 2 has a loudspeaker 4 to which an audio signal from a head unit 3 is supplied, and a vehicle speed pulse signal from a vehicle control computer box 1 is supplied to a CPU 6 of the head unit 3. A muting circuit 8 controlled by a control signal from the CPU 6 is inserted between a reproducing part 5 of the head unit 3 and the loudspeaker 4, and a speed expressed by the vehicle speed pulse signal becomes a speed or more for expressing a preset speed signal when a driver listens to audio voice from the loudspeaker 4, the muting circuit 8 is put in a mute operation state to set the sound volume of an audio from the loudspeaker 4 small or to the wholly inaudible sound volume.
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