Spatial audio reproduction for hearing aid research : System design, evaluation and application

Pausch, Florian; Fels, Janina (Thesis advisor); van Wieringen, Astrid (Thesis advisor)

Berlin : Logos Verlag GmbH (2022)
Book, Dissertation / PhD Thesis

In: Aachener Beitr├Ąge zur Akustik 36
Page(s)/Article-Nr.: 1 Online-Ressource : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2021

Abstract

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 which enable the simulation of indoor scenarios with plausible room acoustics. Inspired by the research question of how to make 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. Systematic objective evaluations led to recommendations of configurations for reliable system operation, accounting for perceptual aspects. The results from perceptual evaluations involving adults with normal hearing revealed that the characteristics of the used research HAs primarily affect sound localisation performance, while allowing comparable egocentric auditory distance estimates as observed when using loudspeaker-based reproduction. To demonstrate the applicability of the system, school-age children with HL fitted with research HAs were tested for speech-in-noise perception in a virtual classroom and achieved comparable speech reception thresholds as a comparison group using commercial HAs, which supports the validity of the HA simulation. The inability to perform spatial unmasking of speech compared to their peers with normal hearing implies that reverberation times of 0.4 s already have extensive disruptive effects on spatial processing 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.

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