Development of noise reduction technique using a pneumatic controll

Abstract

In internal combustion engine development, the relationship between the improvement of engine performance and the reduction of engine noise is a balance; it is very difficult to achieve both objectives, however active noise control (ANC) presents an effective method to address this. With recent advances in digital signal processing technology, ANC, has been used in a number of products. In conventional ANC control, a loudspeaker is often used as an actuator, however the speaker's conversion efficiency is usually too low to control loud noise. In this study, we used a linear motor as the actuator, and examined the possibility of reducing the noise level via the air pressure change in the cabin. We studied the performance of the speaker and the linear motor in controlling a loud noise, and confirmed the effectiveness of the linear motor. It was shown that control of the air pressure change is effective.