On Detectable and Meaningful Speech-Intelligibility Benefits

Whitmer, W. M. , McShefferty, D. and Akeroyd, M. A. (2016) On Detectable and Meaningful Speech-Intelligibility Benefits. In: 17th International Symposium on Hearing (ISH), Groningen, The Netherlands, 15-19 June 2015, pp. 447-455. ISBN 9783319254722 (doi: 10.1007/978-3-319-25474-6_47)

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The most important parameter that affects the ability to hear and understand speech in the presence of background noise is the signal-to-noise ratio (SNR). Despite decades of research in speech intelligibility, it is not currently known how much improvement in SNR is needed to provide a meaningful benefit to someone. We propose that the underlying psychophysical basis to a meaningful benefit should be the just noticeable difference (JND) for SNR. The SNR JND was measured in a series of experiments using both adaptive and fixed-level procedures across participants of varying hearing ability. The results showed an average SNR JND of approximately 3 dB for sentences in same-spectrum noise. The role of the stimulus and link to intelligibility was examined by measuring speech-intelligibility psychometric functions and comparing the intelligibility JND estimated from those functions with measured SNR JNDs. Several experiments were then conducted to establish a just meaningful difference (JMD) for SNR. SNR changes that could induce intervention-seeking behaviour for an individual were measured with subjective scaling and report, using the same stimuli as the SNR JND experiment as pre- and post-benefit examples. The results across different rating and willingness-to-change tasks showed that the mean ratings increased near linearly with a change in SNR, but a change of at least 6 dB was necessary to reliably motivate participants to seek intervention. The magnitude of the JNDs and JMDs for speech-intelligibility benefits measured here suggest a gap between what is achievable and what is meaningful.

Item Type:Conference Proceedings
Glasgow Author(s) Enlighten ID:Whitmer, Dr William and McShefferty, Mr David and Akeroyd, Dr Michael
Authors: Whitmer, W. M., McShefferty, D., and Akeroyd, M. A.
College/School:College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > MRC/CSO SPHSU
Journal Name:Advances in Experimental Medicine and Biology
Publisher:Springer New York
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing: 447-455
Publisher Policy:Reproduced under a Creative Commons License

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