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This Paper Presents the world's first active noise system for production vehicle implementation. Adopted in the new middle size FF car model, this epoch-making system dramatically reduces the booming noise caused by the second-order harmonic of engine revolution. This is accomplished by using an adaptive control theory based on digital signal processing technology and a digital signal processor (DSP). The system basically employs a multiple error filtered-x LMS algorithm, to which an new algorithm was added to achieve the maximum noise reduction effect under a condition of stable control in a compact system for production vehicle application.

The relationship between the spectrum structures of passenger compartment noise and the results of subjective evaluations of sound quality-has been studied on a fron-wheel-drive car with a four cylinder engine. As a result of an analysis using a car interior noise simulator, which is a kind of digital sound shynthesizer, most of the sound quality indicies such as the crank rumble noise, the roughness or unstable characteristics, and the muddiness were found to be related to the structure of engine revolution harmonics and to the strength of fourmants. Further, the physical mechanisms which characterize these spectrum structures were identified through both engine running tests and shaker tests. As a results, the dominant factors governing sound quality problems were found to be the crankshaft bending or torsional vibration coupled with the total power plant vibration shystem.

New image processing procedures for speckle photography and holographic interferometry are described. The algorithm for speckle photography measures the displacement value and direction automatically within the accuracy of ±5% over a range of 10 µm to 150 µm. This algorithm has adopted the Maximum Entropy Method to measure fringe intervals with high accuracy. The algorithm for holographic interferometry detects the fringe line and determines the displacement distribution with an operator's assist. Through the experiments, it was shown that these procedures are effective and accurate for vibration and deformation analysis.