Prevalence and significance of high-frequency hearing loss in subjectively normal-hearing patients with tinnitus

Objectives: We investigated the incidences of high-frequency hearing loss (HFHL; above 2 kHz) and extended high-frequency hearing loss (EHFHL; above 8 kHz) in patients with tinnitus and subjectively normal hearing, and evaluated their effects on the clinical and audiological features of the patients. Methods: The sample included 85 patients with sensorineural tinnitus who had normal hearing sensitivity in the frequencies from 250 Hz to 2 kHz, and who had undergone extended high-frequency audiometry between July 2009 and February 2010. We investigated the incidences of HFHL and EHFHL in these patients and analyzed the significance of the hearing losses. Results: The incidence of HFHL or EHFHL was 88%. The proportion of patients with EHFHL, among the patients who had normal hearing sensitivity up to 8 kHz, was about 74%. The patients with normal hearing sensitivity at all test frequencies were significantly younger, had larger otoacoustic emissions, and had tinnitus that was less loud as measured by tinnitus matching than did the subjects with HFHL and/or EHFHL. However, other comparisons of clinical factors in the three groups did not show any differences. Conclusions: Even if patients with tinnitus do not have any subjective hearing impairment, most of them have HFHL and/or EHFHL. The effects on the clinical features of the patients are still vague.