Will diminishing cochlear delay affect speech perception in noise?

Abstract

Objective: Normal auditory systems appear well habituated to time/phase delays inherent to sound encoding along the hearing organ, sending frequency information non-simultaneously to the central auditory system. Eliminating, or simply perturbing, the cochlear delay might be expected to decrease speech recognition ability, especially under demanding listening conditions. Resources of a larger-scale investigation permitted a preliminary examination of this issue, particularly on a relevant timescale of empirically demonstrated cochlear delays. Design: In a randomized controlled trial study, word recognition was tested for mono-syllabic tokens treated digitally to exacerbate, if not diminish/nullify, such delays. Speech-weighted noise was used to interfere with listening to time-frequency reversed (nominally no delay) versus non-reversed (natural timing) transforms under three treatments of speech tokens: (1) original-digitally recorded; digitally processed to emphasize (2) transient versus (3) quasi-steady-state components. Study sample: Ten normal-hearing young-adult females. Results: The findings failed to demonstrate statistically significant differences between delay conditions for any of the three speech-token treatments. Conclusions: An algorithm putatively diminishing frequency-dependent cochlear delays failed to systematically deteriorate performance in all subjects for the fixed time-frequency transform, stimulus parameters, and test materials employed. Yet, trends were evident such that some effect of perturbing cochlear delays could not be ruled out completely.

Key Words::

• Cochlear delay
• speech recognition in noise
• digital hearing instruments

Acknowledgements

This work was supported in part by a grant from the Office of Naval Research N000140710014 (author JRB, principal investigator). The authors are grateful to the entire research team (members too numerous to mention, but recognized in the publications cited). The authors further are indebted to Jacek Smurzynski, Ph.D., Associate Editor, for his many constructive suggestions and guidance in the management of our submission.

Declaration of interest: The authors report no conflicts of interest.