Speech quality and stable gain trade-offs in adaptive feedback cancellation for hearing aids

Abstract

This paper addresses trade-offs in adaptive feedback cancellation (AFC) for hearing aids. Aggressive AFC for improved added stable gain (ASG) reduces speech quality. In this paper, the hearing-aid speech quality index (HASQI) is used to investigate AFC performance before the system becomes unstable. It is demonstrated that for a desired speech quality, multiple AFC algorithms can be evaluated for their ASG and computational efficiency. An example is presented with HASQI ¼ 0.8, baseline AFC, and two advanced approaches. For the advanced AFCs, ASG gains of 4 and 7 dB were obtained at additional computational complexity of 8% and 11%, respectively.

A Wearable, Extensible, Open-Source Platform for Hearing Healthcare Research

“…Our development of OSP has resulted in novel developments in embedded systems design [10], portable electrophysiology [11], [12], adaptive filtering [13], [14], and other areas not yet published. Yet, the primary novelty of OSPand its primary value to the community-is in its system design as a whole, and the capabilities it offers to researchers and users as a result of this design.…”

“…The AFC generates an estimate of the feedback path using an adaptive finite impulse response (FIR) filter that continuously adjusts its filter coefficients to emulate the feedback path impulse response. Typically the AFC can provide 5-12 dB added stable gain (ASG) [14] depending on the adaptive filtering algorithms used. The RT-MHA implements the least mean square (LMS) based algorithms and features the sparsity promoting LMS (SLMS) [13] which is an advanced adaptive filtering algorithm developed by the OSP team and discussed below (Sec.…”

On Mitigating Acoustic Feedback in Hearing Aids with Frequency Warping by All-Pass Networks

“…For evaluation, we compare the feedback-compensated signal e(n) with the clean signal x(n), using the hearing-aid speech quality index (HASQI) [32] which has been adopted in prior AFC works [14,10,33]. The HASQI score ranges from 0 to 1, where a higher value indicates better quality.…”

“…Finally, we compare the added stable gain (ASG), which is the additional gain due to feedback control mechanism that the HA can still operate in the stable state, for the cases of AFC, AFC with FS, and AFC with freping. We used the ASG estimation approach proposed in [10], where a HASQI below 0.8 was considered of unacceptable quality. The results are shown in Table 1, obtained from the average of 5 male and 5 female speech files.…”

“…Howling artifacts manifest when multiple factors collude to fulfill the magnitude and phase conditions of the Nyquist stability criterion (NSC) [5]. Adaptive feedback cancellation (AFC) has been the work horse for breaking NSC to avoid instabilities in many audio applications [6], including HAs [7,8,9,10]. Typically, the AFC deploys the least mean square (LMS) based approaches to mitigate the magnitude condition in NSC [11,12,13,14].…”