Active control of low frequency engine and road noise inside automotive interiors

Elliott, S. J., Nelson, P. A., Sutton, T., McDonald, A. M., Quinn, D., Stothers, I. M. and Moore, I. (1990) Active control of low frequency engine and road noise inside automotive interiors. Winter Annual Meeting of the American Society of Mechanical Engineers, , Dallas, TX, USA. 25 - 30 Nov 1990. pp. 125-129 .

Abstract

The low frequency noise inside automobiles is largely composed of contributions from the engine and contributions from the tyre rolling along the road. This noise is becoming increasingly dominant in modern light-weight cars and is difficult to control by conventional passive methods without the addition of considerable weight. Active control systems, however, are known to work well at low frequencies, although practical implementations for the control of engine and road noise are rather different because the former is essentially deterministic while the latter is essentially random. Adaptive feedforward control methods can be used in both cases however with a reference signal derived from the ignition system for engine noise and reference signals from an array of accelerometers on the body for road noise. In both cases the coefficients of the adaptive controller are adjusted to minimise the sum of the mean square outputs from a number of microphones inside the vehicle. Practical demonstrations of engine noise control show reductions of 10-15 dB at the engine firing frequency.

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Contributors

Author: P. A. Nelson

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