Analysis of Acoustic Feedback Cancellation Systems based on Direct Closed-Loop Identification

  • Bruno Catarino Bispo Department of Electrical and Electronic Engineering, Federal University of Santa Catarina, 88040-370, Florianópolis, SC, Brazil.
  • Cézar F. Yamamura Department of Electrical Engineering, Federal University of Technology — Paraná, 86300-000, Cornélio Procópio, PR, Brazil
  • Wellington M. S. Nogueira Department of Electrical Engineering, Federal University of Technology — Paraná, 86300-000, Cornélio Procópio, PR, Brazil
  • Edson A. R. Theodoro Department of Electrical Engineering, Federal University of Technology — Paraná, 86300-000, Cornélio Procópio, PR, Brazil
  • Pedro Miguel Rodrigues Universidade Católica Portuguesa, CBQF – Centro de Biotecnologia e Química Fina — Laboratório Associado, Escola Superior de Biotecnologia, 4200-374, Porto, Portugal.

Abstract

This work presents, using the least squares estimation theory, a theoretical and experimental analysis on the performance of the standard adaptive filtering algorithms when applied to acoustic feedback cancellation. Expressions for the bias and covariance matrix of the acoustic feedback path estimate provided by these algorithms are derived as a function of the signals statistics as well as derivatives of the cost function. It is demonstrated that, in general, the estimate is biased and presents a large covariance because the closed-loop nature of the system makes the cross-correlation between the loudspeaker and system input signals non-zero. Simulations are carried out to exemplify the results using speech signals, a long acoustic feedback path and the recursive least squares algorithm. The results illustrate that these algorithms converge very slowly to a solution that is not the true acoustic feedback path. The relationship between the performance of the adaptive filtering algorithms and the aforementioned cross-correlation is proven by varying the signal-to-noise ratio and the delay introduced by the forward path.

Published
25-08-2020
How to Cite
Bispo, B., Yamamura, C., Nogueira, W., Theodoro, E., & Rodrigues, P. (2020). Analysis of Acoustic Feedback Cancellation Systems based on Direct Closed-Loop Identification. Journal of Communication and Information Systems, 35(1), 217-229. https://doi.org/10.14209/jcis.2020.24
Section
Tutorial Papers