gms | German Medical Science

Objectives: Many cochlear implant (CI) recipients use a hearing aid (HA) on the non-implanted ear. Current fitting rules of HAs are optimized on speech rather than music as input. However, a potential improvement might be the transmission of low-frequency acoustic sounds particularly targeting the requirements of music signals. In this project bimodally fitted CI-users are presented with music stimuli that are modified in a standardized and controlled manner and their individual sound quality judgements are collected. The goal is to find possible mechanisms that may be used for HA optimization based on either an individual or generic level.

Design: Non-linear signal processing of the acoustic path is simulated based on the individual pure tone audiogram of the participant using a generic fitting rule. Stimulation is provided by a HA receiver and the CI path transmits the unmodified stimulus via bluetooth to the subject's speech processor. The stimuli consist of acoustic only, electric only, and combined transmission considering several modifications of the acoustic path. Modifications are based on discrimination experiments conducted with the listeners. The MUlti Stimulus test with Hidden Reference and Anchor (MUSHRA) is used to assess sound quality for different stimuli such as classic and pop music with or without lyrics. Outcome of the assessments is determined regarding test-retest reliability, discrimination ability and agreement via the expertise Gauge (eGauge), Lorho et al., 2010.

Results: Here we illustrate the methodology and present our first outcomes of the study.

Conclusions: Based on preliminary results the method seems generally suited for assessment of sound quality in bimodally fitted CI users and for providing information of optimized HA fitting.

Keywords: Bimodal stimulation; sound quality assessment; MUSHRA; eGauge