Beyond the delay barrier in adaptive feedforward active noise control using Youla–Kučera parametrization

Abstract

Adaptive feedforward broad-band noise compensation is currently used when a correlated measurement with the disturbance (an image of the disturbance) is available. Most of the active feedforward noise control systems feature an internal “positive” acoustical feedback between the compensation system and the reference source (a correlated measurement with the disturbance) that has to be taken into account. Adaptive algorithms for active feedforward noise attenuation have been implemented such that the propagation delay between the compensatory actuator and the measurement of the residual noise (the secondary path) be much smaller than the propagation delay between the reference source (image of the incoming noise) and the measurement of the residual noise (the primary path). Nevertheless, there are potential fields of applications in which the propagation delay of the secondary path may be larger than the one of the primary path. The present paper explores the behaviour of the available adaptive feedforward compensation algorithms in this new context. The algorithms have been tested experimentally on a relevant test bench. All the algorithms except the Youla–Kučera finite impulse response (YKFIR) adaptive compensator and the standard FIR adaptive compensator using a stability based filtered adaptation (FUSBA) lead to an unstable behaviour. In terms of performance the YKFIR provides the best performance.