Conclusion: Tinnitus characteristics in normal-hearing patients differ between the groups with unilateral and bilateral complaints.
Objectives: The study was to determine the differences between tinnitus characteristics observed in patients with unilateral vs bilateral symptoms and normal hearing threshold, as well as normal results of distortion-product otoacoustic emissions (DPOAEs).
Method: The patients answered questions concerning tinnitus duration, laterality, character, accompanying symptoms, and circumstances of onset. The results of tympanometry, auditory brainstem responses, tinnitus likeness spectrum, minimum masking level (MML), and uncomfortable loudness level were evaluated. Records of 380 tinnitus sufferers were examined. Patients with abnormal audiograms and/or DPOAEs were excluded. The remaining 66 participants were divided into groups with unilateral and bilateral tinnitus.
Results: Unilateral tinnitus in normal-hearing patients was diagnosed twice more frequently than bilateral. Tinnitus pitch was higher in the group with bilateral tinnitus (p < .001). MML was lower in unilateral tinnitus (p < .05). Mean age of patients was higher in the unilateral tinnitus group (p < .05). Mean tinnitus duration was longer (p < .05) and hypersensitivity to sound was more frequent (p < .05) in the bilateral tinnitus group. Repeated exposure to excessive noise was the most frequent cause in the bilateral tinnitus group.
Keywords: Tinnitus; audiometry; distortion-product otoacoustic emissions; hearing.