Perceptually motivated ANC for hearing-impaired listeners

The goal of noise control in hearing aids is to improve listening perception. In this paper we propose modifying a perceptually motivated active noise control (ANC) algorithm by incorporating a perceptual model into the cost function, resulting in a dynamic residual noise spectrum shaping technique based on the time-varying residual noise. The perceptual criterion to be minimized could be sharpness, discordance, annoyance, etc. As an illustrative example, we use loudness perceived by a hearing-impaired listener as the cost function. Specifically, we design the spectrum shaping filter using the listener's hearing loss and the dynamic residual noise spectrum. Simulations show significant improvements of 3-4 sones over energy reduction (ER) for severe high-frequency losses for some common noises that would be 6-12 without processing. However, average loudness across a wide range of noises is only slightly better than with ER, with greater improvements realized with increasing hearing loss. We analyze one way in which the algorithm fails and trace it to over-reliance on the common psychoacoustic modelling simplification that auditory channels are independent to a first approximation. This suggests future work that may improve performance.