Transient and distortion product evoked oto‐acoustic emissions in normal hearing patients with and without tinnitus

OBJECTIVE: To test the hypothesis that tinnitus begins with outer hair cell dysfunction by recording transient (TEOAE) and distortion product evoked (DPOAE) oto-acoustic emissions in patients with normal hearing with (study group, SG) and without tinnitus (control group, CG). STUDY DESIGN: Case control study. SUBJECTS AND METHODS: SG had 32 patients with pure tone thresholds below 25 dB in the 500 to 8000 Hz interval. CG had 37 age- and gender-matched patients with similar thresholds. All patients had normal tympanograms and stapedial reflexes. TEOAE were recorded with wide band click in continuous mode at 80-dB peak SPL. DPOAE were recorded with f1/f2 = 1.22 and intensities of 65 dB (f1) and 55 dB (f2) SPL. RESULTS: DPOAE were abnormal in 68.4% of SG and in 50% of CG (P = 0.036). TEOAE were abnormal in 70.2% of SG and in 16.10% of CG (P = 0.0001). CONCLUSION: SG had significantly higher prevalence of abnormal TEOAE and DPOAE than CG.