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

Abstract

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.