| 摘要 |
PURPOSE:To heighten suppressing effect of trapped sound by determining phase- lead-lag and amplification degree at the same time for trapped sound frequency of plural order and generating additional sound from an additional sound source at the same time. CONSTITUTION:An ignition signal is made to square wave by a waveform shaper 26, and sent to a controlling circuit 20. In case of 4 cycle engine, trapped sound frequency, twice, four times, six times...2n times rotational frequency is calculated based on the square wave outputted from the waveform shaper 26, and phase-lead-lag and amplification degree corresponding to these trapped sound frequency are calculated, and outputted from a speaker 22 installed at a specified position of a vehicle according to phase-lead-lag for each determined frequency, and works as an additional sound source that outputs converted sound as additional sound. Thus, trapped sound frequency of wide range can be suppressed. |
