Second Biennial Hearing Aid Research and Development Conference
September 22-24, 1997
National Institutes of Health
Listening Comfort of Real and Artificial Hearing-aid Processed Speech
Niek J. Versfeld,
Department of Otolaryngology, University Hospital VU, Amsterdam, The Netherlands
In order to assess the relative importance of various signal processing algorithms and distortions on listening comfort, male and female speech was manipulated in a number of ways and subsequently presented to normal-hearing and hearing-impaired subjects (the latter having a mild sensorineural high-frequency hearing loss). Signal manipulations were artificial (e.g., filtering, compression limiting, peak clipping, or adding noise) or were actual dummy-head recordings of five different hearing aids. Listeners judged the sounds in a pairwise-comparison format. Their task was to indicate the "hearing aid" they would prefer assuming they had to wear it all day.
The results show that normal-hearing subjects preferred the original signal, whereas hearing-impaired subjects were inclined to choose the signals with a high-frequency emphasis. Severe band-pass filtering or low-frequency emphasis considerably degrades listening comfort, as was to be expected. Surprisingly, however, a soft background noise (S/N ratio of 25 dB) already decreases listening comfort enormously. The listening comfort scores for the five hearing aids were very similar, despite the fact that their frequency responses are rather different. Between-subject differences were evident, and multidimensional analysis reveals that the first two dimensions on which listening comfort was based, can be interpreted as (1) intelligibility and (2) signal distortion.
[Work supported by Philips Hearing Instruments BV, Eindhoven, The Netherlands]
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