Abstract
Background: The influence of tinnitus on speech reception is under debate. A few previous studies addressed this issue and compared speech reception in groups with and without tinnitus, with tinnitus arising in both ears or in the same test ear. Recently, we demonstrated that loudness of tinnitus in single-sided deafness (SSD) could be reduced dramatically by implanting and activating a cochlear implant (CI).
Purpose: The aim of the study was to evaluate whether changing the level of tinnitus in the SSD ear by disenabling or enabling the CI changes the speech reception in noise in the non-tinnitus ear.
Methods and Patients: Fifteen CI users (MED-EL multichannel) with SSD and incapacitating tinnitus participated. They had an initial score of 6 or greater out of 10 on the Visual Analogue Scale (VAS) and an average total score of 58.05 (standard deviation [SD], 13.68) on the Tinnitus Questionnaire. The outcome measure, speech reception threshold (SRT) in noise using an adaptive procedure was measured in the nontinnitus ear using insert earphones. The measurements were performed with a high tinnitus level and a low tinnitus level in the SSD ear, realized by switching the CI off or on. Tinnitus loudness was assessed on a VAS, and tinnitus loudness was also matched using an audiometer.
Results: Speech reception in noise is significantly worse in case of high tinnitus loudness. The mean difference in SRT in the nontinnitus ear between the 2 conditions (SRTCI off-SRTCI on) of the 15 subjects was 1.98 dB SNR (SD, 3.01 dB SNR). The mean tinnitus loudness on the VAS was 7.2 (SD, 2.6) in the CI-off condition. In the CI-on condition, the mean VAS score significantly declined to 3.4 (SD, 2.5). Also, the tinnitus loudness match improved from 22 dB SL (SD, 14.4 dB SL) to 10 dB SL (SD, 10.1 dB SL) in the CI-on condition.
Conclusion: Unilateral tinnitus can significantly decrease speech reception in noise in the nontinnitus ear.