Evaluation of auditory temporal processing in patients fitted with bone-anchored hearing aids.

Purpose: The present study aimed to identify temporal processing abilities in users of bone-anchored hearing aid (BAHA).

Methods: Seventeen subjects with BAHA (SWB) users and 29 subjects with normal-hearing were compared using the frequency pattern test, duration pattern test, and speech-in-noise test. Besides behavioral temporal processing tests, a multi-feature mismatch negativity (MMN) test was performed in BAHA users to assess the accuracy of objective auditory discrimination at the cortical level, irrespective of the subjects' attention or behavioral task.

Results: The results of the multi-feature MMN test showed that BAHA users could perceive differences in frequency, duration, intensity. However, no response was elicited regarding localization of stimulus and gaps within tones. Word recognition performance in noise was significantly poorer compared with normal hearing groups. All age groups showed no differences in terms of temporal processing abilities except 30-39 years duration pattern ability weaker in SWB group.

Conclusion: The present study was the first to indicate that the use of unilateral BAHA has no effect on the localization of auditory stimuli at the cortical level according to electrophysiological test. Although Baha users have near-normal levels of hearing thresholds and temporal ordering abilities with their devices, since they benefit from the unilateral device, they still have some difficulties in resolution, recognizing and distinguishing the spatial aspects of speech, especially in multiple and noisy listening environments.