An integrated approach for Noise Reduction and Dynamic Range Compression in hearing aids

Hearing aids typically use a serial concatenation of Noise Reduction (NR) and Dynamic Range Compression (DRC). However, the DRC in such a concatenation negatively affects the performance of the NR stage: the residual noise after NR is amplified by the DRC, resulting in a signal-to-noise-ratio (SNR) degradation. In this paper, we present an integrated solution for NR and DRC. The solution is based on an estimate of the amount of speech and noise in each time segment. In case the speech is dominant, the NR is less active and it is desirable to have as much DRC as possible, whereas in a noise dominant segment the NR is more active and the idea is not to compromise this operation by applying DRC. Experimental results confirmed that a serial concatenation of NR and DRC degrades the SNR improvement, and that the proposed solution offers a better SNR improvement compared to a serial concatenation.