| 摘要 |
PURPOSE:To reduce noises of an engine, by composing part of an enclosure of a board speaker, and vibrating and controlling said speaker in such a way that the vibrations of the speaker are at the same level as that of the enclosure caused by the noises of the engine and the phase of said speaker is opposite to that of said noises. CONSTITUTION:The enclosure 5 mounted to cover an engine 2 is composes of a board speaker. The vibrations of the enclosure 5 caused by the noises of the engine in the engine room 8 are detected by a vibration detecting sensor 9, and the detected signal is sent to a filter section 12 of a controller 11. This signal is analysed in the filter section 12 with respect to the frequency, and its amplitude and phase are detected by an amplitude detecting section 13 and a phase detecting section 14. The analysed and detected results are sent to an arithmetic section 15. The arithmetic section 15 carries out computation based upon the results, and the enclosure 5 is vibrated and controlled by the computed result in such a way that it is vibrated approximately at the same frequency and level as those of the vibrations of said noises and with an antiphase to that of the vibrations of said noises. |
