Study on Active Booming Noise Control through Car Interior Sound Field Analysis.

With the aim of reducing “booming noise”, which is one of the major noise problems for 4-cylinder-engine vehicles, a basic study on active noise control (ANC) has been carried out. First, the interior sound field was examined in terms of its fluctuation characteristics, which eventually led to the confirmation that an adaptive technique is necessary. The multiple-error filtered-x LMS (MEFX) algorithm was then found to be effective through an “off-line” shaker test on a real car. Secondly, the acoustic intensity method was applied to analysis of the sound field inside a car. Actuator (speaker) positioning was considered based on this analysis of standing wave and traveling wave contribution. In addition, the controller parameters' influence on control performance was estimated by means of computer simulation. Guidelines were developed for applying this technique to automobiles. ANC was found to be capable of reducing booming noise by more than l0 dB.