Prospective case-controlled sound localisation study after cochlear implantation in adults with single-sided deafness and ipsilateral tinnitus.

ABSTRACT

OBJECTIVES: To analyse the sound localisation skills of subjects with profound single-sided deafness (SSD) and accompanied ipsilateral tinnitus who are using a cochlear implant (CI) for between 4 and 11 years. DESIGN: Sound localisation skills were tested using nine loudspeakers in a frontal semicircle ranging from -90° to +90°. Subjects were tested in the CION and the CIOFF conditions via 3 localisation stimuli broadband noise (BB), low-pass noise (LP) and high-pass noise (HP). PARTICIPANTS: The test group consisted of 10 adult subjects with profound sensorineural SSD, ipsilateral tinnitus and a CI. Normative data of a control group of 30 normal hearing subjects were used for comparison. MAIN OUTCOME MEASURES: Sound location accuracy was analysed via the root-mean-square error (RMSE), the mean absolute error (MAE), the localisation bias ('b') and the bias-adjusted deviation ('db '). Subjective dynamic aspects of hearing were assessed via a reduced version of the Speech, Spatial and Qualities of Hearing Scale (SSQ5 ). RESULTS: For all 3 stimuli, the RMSE improved significantly in SSD subjects in the CION condition compared to the CIOFF condition. The localisation accuracy of subjects with SSD improved significantly for BB and HP stimuli. A significant bias-adjusted deviation 'db ' was found for the BB and HP stimuli. Subjects' mean SSQ5 scores were significantly higher in the CION condition at test date than in the CIOFF condition preoperatively. CONCLUSIONS: Subjects can better locate sound in the CION condition than in the CIOFF condition.