Modeling horizontal localization of complex sounds in the impaired and aided impaired auditory system

Background noise, room reflections, or interfering sound sources represent a challenge for daily one-to-one communication, particularly for hearing-impaired listeners, even when wearing hearing aid devices. Through a modeling approach, this project investigated how peripheral hearing loss impairs the processing of spatial cues in adverse listening conditions. A binaural model in which the peripheral processor can be tuned to account for individual hearing loss was developed to predict localization in anechoic and reverberant rooms. Hearing impairment was accounted for by a loss of sensitivity, a loss of cochlear compression and reduced frequency selectivity. A spatial cue-selection mechanism processed the output of the binaural equalization-&-cancellation processor to evaluate the localization information’s reliability based on interaural coherence. The simulations in anechoic environment suggested that the sound-source-location estimates become less reliable and blurred in the case of reduced audibility. Simulations in rooms suggested that the broadening of the auditory filters reduces the fidelity of spectral cues and affects the internal representation of interaural level differences. The model-based analysis of hearing-aid processing showed that amplification and compression used to recover audibility also partially recovered the internal representation of the spatial cues in the impaired auditory system. Future work is needed to extend and experimentally validate the model. Overall, the current model represents a first step towards the development of a dedicated research tool for investigating and understanding the processing of spatial cues in adverse listening conditions, with a long-term goal of contributing to solving the cocktail-party problem for normal hearing and hearing-impaired listeners.