Masking effects in patients with auditory neuropathy-possible involvement of suppression mechanism caused by normal outer hair cell function.

OBJECTIVE

Variations in the effects of masking noise were evaluated in different pathologies of sensorineural hearing loss.

STUDY

DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS: Fifty-five ears of 30 patients with sensorineural hearing loss who underwent noise audiometry in the Department of Otolaryngology-Head and Neck Surgery, Tohoku University Hospital, since 2010, because of complaints of hearing difficulty in noisy environments.

MAIN OUTCOME MEASURES: Masked threshold for narrow band and white noise.

RESULTS AND DISCUSSION: Masking effects in patients with auditory neuropathy were significantly larger than those in patients with other types of hearing losses. Masking effects of broad band white noise were greater than those of narrow band noise. Masking effects could be observed for white noise even in the elevated unmasked threshold region, where little contribution of excitatory masking effect would be expected. The present findings support the idea that the suppression mechanism caused by normal outer hair cell function is important in the masking phenomenon in patients with auditory neuropathy.