| 摘要 |
PURPOSE:To eliminate the trouble of more increasing a volume while stopping a car since frequency components caused by the revolving speed at the time of idling an engine are concentrated to a super-low frequency in the case of controlling the electronic volume with a microcomputer corresponding to the level by detecting the super-low frequency component of noise in the car concerning the automatic volume control of an on-vehicle audio equipment. CONSTITUTION:The super-low frequency component of noise collected by a microphone 1 is divided by band pass filters 3a-3f for plural bands and inputted to a control microcomputer 5. On the other hand, the control microcomputer 5 converts the revolving speed inputted from an engine revolution meter 6 to an explosion speed, the noise of a band corresponding to the frequency band is subtracted from inputs from the band pass filters 3a-3f and corresponding to the level of the result, an electronic volume 11 is controlled. |
