Hearing impairment and tinnitus pitch in patients with unilateral tinnitus: comparison of sudden hearing loss and chronic tinnitus

OBJECTIVES: The objectives were to analyze the results of pitch-matching and loudness-balance testing in patients with unilateral tinnitus and to evaluate the relationship between audiological findings based on the tinnitus-affected and tinnitus-unaffected threshold differences and tinnitus pitch by using linear interpolation methods. In addition, the effects of the duration of the tinnitus on this relationship were investigated. Sudden sensorineural hearing loss with tinnitus was selected for the "acute tinnitus" group, and unilateral tinnitus with unknown disease and a duration of more than 3 months was selected for the "chronic tinnitus" group. STUDY DESIGN: Retrospective study of the clinical records of patients. METHODS: One hundred thirty-two patients with unilateral tinnitus (comprising 68 female [51.5%] and 64 male [48.5%] patients) were investigated as subjects. Their mean age was 50.4 years (SD = 15.8 y). All patients underwent otoneurological testing, including the pure-tone audiogram and pitch-matching and loudness-balance tests. RESULTS: The mean difference in the hearing threshold between the tinnitus-affected ear and the tinnitus-unaffected ear was largest near the tinnitus pitch in both the acute and the chronic tinnitus groups. However, the relationship between hearing impairments and tinnitus pitch was somewhat different in the two groups: It exhibited a single smooth peak in the acute tinnitus group but a bimodal peak in the chronic tinnitus group. CONCLUSION: The results suggest that tinnitus is related to hearing impairment in the same frequency region in patients with sudden sensorineural hearing loss with tinnitus or in patients with chronic tinnitus, whereas some instances of chronic tinnitus are caused by reorganization in cortical cells.