Optimal uses of feedforward type and feedback type adaptive control algorithms in active noise control

Abstract

One‐dimensional active noise control problems such as canceling noise propagating down a duct or longitudal vibration within a structural vibration mount are considered, in general, to be well suited for active noise control. However (through the use of feedback control), active noise control can also be successful in applications where there are many sources of noise and low coherence between possible sensor locations. Feedback control requires only an error sensor and an actuator to minimize the noise at the error sensor. There is no question that if all the noise components at a sensor location can be observed before the noise propagates to the actuator and error sensor, then the best choice of controller involves a feedforward algorithm. However, if the noise propagates faster than the actuator can respond (a good example is high‐frequency bending waves), random impacts or spectrally white noise cannot be canceled and complexity can be reduced by using feedback control to obtain the same theoretical performance. Feedback control also allows multiple periodic noise sources to be controlled using a single control loop.