| 摘要 |
PROBLEM TO BE SOLVED: To provide an on-vehicle acoustic device outputting easily audible sound by masking a noise generated by the revolution of an engine of a vehicle with a sound. SOLUTION: The on-vehicle acoustic device includes a ripple detection part 2 for detecting a ripple voltage superimposed on a battery voltage supplied to a power source 12 of the on-vehicle acoustic device, a microcomputer 10 for calculating the engine speed based on the detected ripple frequency information, and a sound processing part 3 for adjusting a sound volume and sound frequency characteristics. The on-vehicle acoustic device automatically adjusts a sound volume and sound frequency characteristics based on the engine speed. COPYRIGHT: (C)2011,JPO&INPIT
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