Adaptive modelling of digital hearing aids using a subband affine projection algorithm

Adaptive modeling of digital hearing aids is useful in characterizing the hearing aid behavior in response to “real world” stimuli such as speech and music. Most modern hearing aids employ amplitude compression in different frequency bands for effective mapping of the wide dynamic range audio signals into the reduced dynamic range of the hearing impaired listeners. Due to the presence of independent compression channels, the conventional fullband adaptive model might not adequately characterize the performance of a multichannel compression hearing aid (MCHA). In this paper, we propose a subband adaptive modeling approach to characterize the electroacoustic performance of a MCHA. The proposed structure employs uniform, oversampled DFT filterbanks for analysis and synthesis, and the affine projection algorithm for adaptive modeling in each subband. Experiments with simulated MCHAs showed that the subband structure outperforms the fullband structure under a variety of operating conditions.