Postfiltering in Adaptive Feedback Cancellation for PA Systems

Bachelor thesis (2020)

Authors

C.A. Weustink Electrical Engineering, Mathematics and Computer Science
J.W. de Vries Electrical Engineering, Mathematics and Computer Science

Contributors

R.C. Hendriks Signal Processing Systems - EEMCS (supervisor 1)
Jorge Martinez Electrical Engineering Education - EEMCS (supervisor 1)
J.E.J. Schmitz Electrical Engineering, Mathematics and Computer Science (supervisor 2)
S. Izadkhast Electrical Engineering Education - EEMCS (supervisor 2)
M. Çalış Signal Processing Systems - EEMCS (supervisor 2)
Faculty
Electrical Engineering, Mathematics and Computer Science
Copyright: © 2020 C.A. Weustink, J.W. de Vries
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Published Date

02-07-2020

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Abstract

The most promising method for acoustic feedback control in public address systems is adaptive feedback cancellation (AFC). This approach is based on making an estimation of the room impulse response, which is used to subtract an estimate of the feedback from the microphone signal. A postfilter is often used to improve the performance of such an AFC system by reducing residual feedback or increasing stability. The postfilter implemented in this thesis focuses on the latter. It consists of two modules: howling detection and howling suppression. The final design makes use of the peak to harmonic power ratio criterion (PHPR) and second order digital Butterworth notch filter respectively. Simulation measurements show a successful suppression of howling as long as the loudspeaker signal does not
get saturated.