Individual Differences Underlying Preference for Processing Delay in Open-Fit Hearing Aids

In open-fit digital hearing aids (HAs), the processing delay influences comb-filter effects that arise from the interaction of the processed HA sound with the unprocessed direct sound. The current study investigated potential relations between preferred processing delay, spectral and temporal processing abilities, and self-reported listening habits. Ten listeners with normal hearing and 20 listeners with mild-to-moderate sensorineural hearing impairments participated. Using a HA simulator, delay preference was assessed with a paired-comparison task, three types of stimuli, and five processing delays (0, 0.5, 2, 5, and 10 ms). Spectral processing was assessed with a spectral ripple discrimination (SRD) task. Temporal processing was assessed with a gap detection task. Self-reported listening habits were assessed using a shortened version of the 'sound preference and hearing habits' questionnaire. A linear mixed-effects model showed a strong effect of processing delay on preference scores (p < .001, η²= 0.30). Post-hoc comparisons revealed no differences between either the two shortest delays or the three longer delays (all p > .05) but a clear difference between the two sets of delays (p < .001). A multiple linear regression analysis showed SRD to be a significant predictor of delay preference (p < .01, η²= 0.29), with good spectral processing abilities being associated with a preference for short processing delay. Overall, these results indicate that assessing spectral processing abilities can guide the prescription of open-fit HAs.