Sound quality evaluation of a speech enhancement algorithm for hearing impaired listeners

Abstract

Difficulty of understanding speech in noise environment has been one of the most common complaints of hearing aid users. Various speech enhancement algorithms have been applied to digital hearing aid to improve speech perception in noise environment. In this study, a speech enhancement algorithm using both spectral subtraction and companding is proposed for digital hearing aids. Objective evaluation, spectrogram comparison and subjective evaluation under various environmental conditions were performed. We tested Segmental SNR (Signal to Noise Ratio) and Log Likelihood Ratio (LLR) for objective evaluation. For subjective evaluation, Mean Opinion Score (MOS) that represented the global perception score was performed to 10 normal listeners and 9 hearing aid users. Also, we measured Speech Reception Threshold (SRT) of hearing aid users based on the 50%-correct point in terms of SNR. Statistical comparisons of all methods were performed using the Wilcoxon signed rank test with 0.05 significant levels. All of the results using objective and subjective evaluation show that the proposed speech enhancement algorithm is beneficial for hearing aid users in diverse noisy environments.