The effects of unilateral tinnitus on auditory temporal resolution: gaps-in-noise performance.

Background And Objectives: The Gaps-In-Noise (GIN) test is a measure to assess auditory temporal resolution, which is the ability to follow rapid changes in the envelope of a sound stimulus over time. We investigated whether unilateral tinnitus affects temporal resolution by the GIN performance.

Subjects And Methods: Hearing tests including the GIN test were performed in 120 ears of 60 patients with unilateral tinnitus who showed symmetric hearing within 20 dB HL difference up to 8 kHz (tinnitus-affected ears, 14.6±11.2 dB HL; non-tinnitus ears 15.1±11.5 dB HL) and 60 ears of 30 subjects with normal hearing. Comparisons were made between tinnitus and non-tinnitus side of patients and normal ears of controls.

Results: There was no significant difference of the mean GIN thresholds among tinnitus-affected ears (5.18±0.6 ms), non-tinnitus ears (4.98±0.6 ms) and normal ears (4.97±0.8 ms). The mean percentage of correct answers in tinnitus side (67.3±5.5%) was slightly less than that in non-tinnitus side (70.0±5.5%) but it was not significantly different from that in normal ears (69.4±7.5%). Neither the GIN threshold nor the GIN perception level in tinnitus ears has relation to sex, frequency and loudness of tinnitus, and audiometric data. Age only showed a significant correlation with the GIN performance.

Conclusions: We found no evidence which supported the influence of unilateral tinnitus on auditory temporal resolution. These results imply that tinnitus may not simply fill in the silent gaps in the background noise.