Three-channel variable filter-bank for digital hearing aids

This paper proposes a three-channel (3-channel) variable filter-bank (VFB) that consists of variable lowpass, variable bandpass, and variable highpass digital filters. The three variable digital filters are obtained from a normalized analog prototype Chebyshev type-I lowpass filter using analog frequency transformations along with a modified bilinear transformation. Since both the magnitudes (gains) and band edge frequencies of the three variable digital filters are independently adjustable, the 3-channel VFB is considerably flexible, and can be successfully applied for compensating various hearing loss patterns in digital hearing aids. Various audiograms have been used to verify that high-accuracy fittings can be achieved with only low order (second-order) variable filters.