A low-complexity 3-level filter bank design for effective restoration of audibility in digital hearing aids

A low-complexity method for sub-band decomposition of audio signals in digital hearing aids for audibility restoration applications is described in this paper. This 3-level filter bank is capable of generating an array of 4, 8, and 16 sub-filters from a single finite impulse response filter. The prototype low pass filter is accomplished using the Parks McClellan algorithm with a minimal number of 28 multipliers. Fractional interpolation technique is utilized to generate more number of sub-bands with narrow bandwidth from the prototype filter. This filter bank can be used for patients with any degree of hearing impairment to compensate his audiogram. The selection of filter bank is based on the rate of change of impairment recorded in the audiogram. Apart from reduced complexity, the developed filter bank has the advantage of requiring only minimal hardware, which makes the implementation of cost-effective hearing aids a reality.