Auditory rehabilitation effects on speech lateralization in hearing-impaired listeners

Previous studies reported that the consequences of auditory rehabilitation were lateralized, with the right ear (RE) showing more improvement than the left ear (LE) over the time course of hearing aid (HA) use in elderly patients with symmetrical presbyacusis. It has been suggested that this asymmetry is linked to a change in speech lateralization. The aim of this study was to explore the consequences of HA use on interaural asymmetry in symmetrical sensorineural hearing impairment patients before and 4 months after binaural HA fitting.

Two types of perceptual task were chosen in order to measure speech lateralization: two dichotic listening tasks; and an identification task for a voice onset time continuum. Seven elderly, right-handed patients suffering from symmetrical presbyacusis were selected and tested before HA fitting and 4 months after. All measurements were made without the use of the HA, and the listeners were all first-time HA wearers.

Dichotic listening scores for words improved significantly over the course of HA use. Moreover, the dichotic listening task for syllables revealed an increase in auditory asymmetry after 4 months of HA use. Concerning the identification task, a significant difference between ears was found, with only the R E showing significant improvement with HA use.

These results suggest that auditory rehabilitation is lateralized, with greater change as a result of HA use occurring in the RE than the LE in right-handed patients.