This paper is concerned with the analysis and design of an integrated passive and active control system for reducing the haul truck noise. By using a passive enclosure with two open ends and fiberglass inner surface, a three-dimensional noise radiation problem of the engine noise is shaped to a simple problem of noise radiation from the open ends above 200 Hz. Below 200Hz where the transmission loss of the lightweight enclosure is low, a spatial global active noise control (ANC) system is constructed inside the enclosure. To improve the performance of the system, the open ends are divided into four equal diameter size ducts each followed by a louver. A single channel ANC system is set up in each duct to eliminate the noise in the frequency range from 200 Hz to 400 Hz. Experimental results demonstrate that more than 20 dB insertion loss is achieved with such a passive enclosure at frequency band above 400 Hz, and 8 dB noise reduction with global ANC systems at frequency band below 200 Hz, and 4 dB noise attenuation with single channel ANC systems between 200 Hz and 400 Hz. The results this investigation show the feasibility of hybrid noise control technique for reducing the haul truck noise.
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