Statistical Analysis of the Bias in Acoustic Feedback Cancellation System for Hearing Aids

The acoustic feedback is one of the main complaints hearing aids users producing distortion of the desired signal and limiting the maximum hearing aid’s stable gain. The acoustic feedback cancellation system here presented employs an LMS adaptive estimator and an LMS adaptive predictor operating simultaneously. The nature of the practical problem makes the input to the adaptive estimator and the interference to its output statistically correlated, thus a biased solution is found. This paper presents an analytical model for the bias and the performance of the system is then investigated. Interesting results were obtained from the model. Monte Carlo simulations are presented to verify the accuracy of the derived model.