Design of ANSI S1.11 Filter Bank for Digital Hearing Aids

Existing digital hearing aids, to our knowledge, all exclude ANSI S1.11-compliant filter banks because of the high computational complexity. Most ANSI S1.11 designs are IIR- based and only applicable in applications where linear phase is not important. This paper presents an FIR-based ANSI S1.11 filter bank for digital hearing aids, which adopts a multi-rate architecture to reduce the data rates on the bandwidth-limited bands. A systematic way is also proposed to minimize the FIR orders thereof. In an 18-band digital hearing aid with 24 kHz input sampling rate, the proposed design with linear phase has comparable computational complexity with IIR filter banks. Moreover, our design requires only 4% multiplications and additions of a straightforward FIR implementation.