The effect of multichannel dynamic compression on speech intelligibility.

In the recent literature on dynamic compression in hearing aids, a controversial discussion about the benefit of multichannel compression with short time constants has been raised. In this paper, some experimental results are contributed to the discussion: For low signal-to-noise ratios, a detrimental effect of fast multichannel compression on speech intelligibility in normal hearing listeners is found. However, a distinct degradation in speech quality and virtually no decrease in speech intelligibility is observed for comparatively high signal-to-noise ratios and compression ratios of up to 3. Since the predictions of the Speech Transmission Index deviate substantially from these results, its applications as an objective measure of intelligibility may not be extended to compressed speech.