Spatial Audio Reproduction for Hearing Aid Research: : System Design, Evaluation and Application

Hearing loss (HL) has multifaceted negative consequences for individuals of all age groups. Despite individual fitting based on clinical assessment, consequent usage of hearing aids (HAs) as a remedy is often discouraged due to unsatisfactory HA performance. Consequently, the methodological complexity in the development of HA algorithms has been increased by employing virtual acoustic environments, allowing simulation of indoor scenarios with plausible room acoustics. With the aim of making such environments accessible to HA users while maintaining complete signal control, a novel concept addressing combined perception via HAs and residual hearing is proposed. The specific system implementations employ a master HA and research HAs for aided signal provision, and loudspeaker-based spatial audio methods for external sound field reproduction. Recommendations on system configurations for a stable operation on desktop computers are provided. The results from perceptual evaluations involving adults with normal hearing primarily indicate adverse effects on localisation performance and less on egocentric distance perception when using the research HAs. Within the scope of the system application, school-age children with HL fitted with research HAs achieved similar speech reception thresholds in a virtual classroom as a comparison group using their own HAs. It is further shown that reverberation times of 0.4 s already have extensive disruptive effects on spatial unmasking abilities in children with HL. Collectively, the results from evaluation and application indicate that the proposed systems satisfy core criteria towards their use in HA research.