Reconfigurable Nonuniform Filter Bank for Hearing Aid Systems

Filter banks with good reconfigurability are desired in hearing aid systems due to the individual requirements of patients with different hearing loss characteristics. This paper proposes a modularized design approach of a completely reconfigurable nonuniform filter bank for hearing aid systems. The proposed filter bank structure consists of a multiband generation module and a subband extraction module, where the frequency warping technique is adopted. Based on theoretical analyses of second order frequency warping, the subband distribution can be flexibly controlled. Moreover, to adapt the subband extraction module design to the multiband generation module, the relationship between control parameters is analyzed and a mapping formula is derived. Through the co-design of the two modules, superior reconfigurability over existing methods is achieved. Application examples show that the proposed filter bank is able to provide multiple subbands distribution schemes that satisfy the requirements of different audiograms. The proposed filter bank structure has lower complexity, smaller delay and smaller matching errors than existing filter bank structures due to its flexible structure.