Single Sided Deaf Cochlear Implant Users in the Difficult Listening Situation: Speech Perception and Subjective Benefit.

Objectives: Patients with single-sided deafness (SSD) have great difficulties in listening situations which rely on binaural auditory processing. The purpose of this study was to examine to which extent a cochlear implant (CI) can improve speech perception outcomes in various noisy listening environments. Additionally, the ability to use interaural level differences for sound localization and subjective benefit with the CI were assessed.

Methods: Ten single-sided deaf patients with CI were tested in different loudspeaker configurations with and without the CI. A multi-source noise field (MSNF) with uncorrelated noise from four different directions was used in addition to a setup with the signal from the CI side and noise from the normal-hearing side (SCINNH, azimuth of ±45 degrees). Ten normal-hearing subjects were used as a control for the setup. Speech understanding was measured by an adaptive sentence test (Oldenburg Sentence Test, OLSA) in stationary speech shaped noise and temporally modulated noise to assess the benefit in each listening situation. Sensitivity to interaural level differences was measured in a lateralization experiment. Furthermore, patients completed the Bern Benefit in Single-Sided Deafness (BBSS) questionnaire to assess subjective benefit with the CI.

Results: An overall average benefit in speech reception threshold (SRT) of 1.6 dB (±0.6 dB standard error of the mean [SEM]) was observed in the binaural listening condition (with CI) in all conditions. In the MSNF setup thresholds improved by 0.4 dB (±0.5 dB SEM) and in the SCINNH configuration by 2.7 dB (±0.7 dB SEM). The choice of masking noise effect also had a significant effect on the SRT outcome. The lateralization performance of the SSD users was on a par with the normal hearing group. BBSS scores reflect the overall benefit with the CI apparent in the speech test results.

Conclusion: Patients with single-sided deafness do benefit from a CI in difficult listening environments and are able to localize sound based on interaural level differences. Considering these outcomes, cochlear implantation represents a promising treatment option for patients with single-sided deafness.