Associations Between Physiological Indicators of Cochlear Deafferentation and Listening Effort in Military Veterans with Normal Audiograms

In a sample at high risk for noise-induced cochlear deafferentation (military Veterans with clinically normal audiograms), this study evaluated the relationship between physiological indicators of cochlear deafferentation (ABR, EFR, and MEMR) and listening effort, as indicated by pupil dilation during a speech perception in noise task. The hypotheses were that: 1) listening effort would be greater among participants with weaker ABR, MEMR, and EFR responses relative to participants with stronger responses and 2) physiological indicators of deafferentation would have stronger associations with listening effort than with speech perception performance.

Reductions in ABR and EFR measurements were associated with greater task-related pupil dilation, but not with reduced speech perception in noise performance. This suggests that cochlear deafferentation may result in increased listening effort during speech-in-noise perception, even if performance on the task is not negatively impacted. The observed relationship between EFR magnitude and pupil dilation was non-linear, suggesting that increased listening effort may only occur after a particular threshold level of deafferentation has been reached.