On detectable and meaningful speech-intelligibility benefits

Whitmer, William M.; McShefferty, David; Akeroyd, Michael A.

Abstract

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.

Citation

Whitmer, W. M., McShefferty, D., & Akeroyd, M. A. (in press). On detectable and meaningful speech-intelligibility benefits. Advances in Experimental Medicine and Biology, 894, https://doi.org/10.1007/978-3-319-25474-6_47

• Journal Article Type: Article
• Acceptance Date: Dec 1, 2015
• Online Publication Date: Apr 15, 2016
• Deposit Date: Nov 16, 2016
• Publicly Available Date: Nov 16, 2016
• Journal: Advances in Experimental Medicine and Biology
• Electronic ISSN: 0065-2598
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 894
• DOI: https://doi.org/10.1007/978-3-319-25474-6_47
• Keywords: Signal-to-noise ratio, Just-noticeable difference, Speech intelligibility, Hearing impairment
• Public URL: https://nottingham-repository.worktribe.com/output/785152
• Publisher URL: http://link.springer.com/chapter/10.1007%2F978-3-319-25474-6_47
• Additional Information: Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing / editors, Hearing. Editors: Pim van Dijk, ; Deniz Baskent, Etienne Gaudrain, Emile de Kleine, Anita Wagner, Cris Lanting. ISBN 9783319254746.
• Contract Date: Nov 16, 2016