| 摘要 |
PURPOSE:To obtain trapped sound suppressing effect by generating additional sound from specific additional sound sources arranged at plural places in a vehicle based on phase-lead-lag of trapped sound frequency and amplification degree. CONSTITUTION:An ignition signal is made to square wave by a waveform shaper 26 and sent into a controlling circuit 20, and trapped sound frequency is calculated on the basis of square wave outputted by the waveform shaper 26. Phase-lead-lag and amplification degree corresponding to a specifiec speaker is calculated based on the trapped sound frequency, and outputted to each speaker 22 from the controlling circuit 20 according to determined phase- lead-lag. Thus, additional sound is generated from specific speaker corresponding to acoustic mode of respective trapped sound frequency, wider suppressing effect can be obtained for wide range of trapped sound frequency. |
