Otoacoustic emissions as a part of the test battery for tinnitus diagnosis

Abstract

Tinnitus is a common auditory phenomenon that often occurs in the absence of measurable hearing loss, posing challenges for accurate diagnosis and early intervention. This study explored the diagnostic potential of high-frequency distortion product otoacoustic emissions (HF-DPOAEs) in detecting subclinical cochlear dysfunction in adults with tinnitus and clinically ‘normal’ hearing. Forty participants aged 19-40 were recruited and divided into two groups: 25 individuals with subjective tinnitus and 15 age-matched controls. All participants had hearing thresholds ≤20 dB HL (250 Hz-8 kHz) and type A tympanograms, confirming ‘normal’ peripheral auditory function. DPOAEs were recorded across a frequency range of 988 Hz to 12,000 Hz. Comparative analysis of DPOAE amplitudes revealed no significant differences between groups at frequencies ≤4444 Hz. However, the tinnitus group exhibited consistent reductions in emission amplitudes at select high frequencies, with pronounced declines observed at 6154 Hz, 8000 Hz, 8889 Hz, and 10,000 Hz. While these differences did not always retain statistical significance after correction for multiple comparisons, a persistent trend emerged, suggesting diminished outer hair cell function in the tinnitus group at apical cochlear regions. These findings suggest that HF-DPOAEs may serve as a sensitive, non-invasive measure for identifying early-stage outer hair cell dysfunction in individuals with tinnitus, even when conventional audiometry appears ‘normal’. Incorporating extended-frequency OAE testing into routine audiological assessments may enhance the early detection and management of tinnitus-related cochlear changes.