Title :
10-ms 18-Band Quasi-ANSI S1.11 1/3-Octave Filter Bank for Digital Hearing Aids
Author :
Chih-Wei Liu ; Kuo-Chiang Chang ; Ming-Hsun Chuang ; Ching-Hao Lin
Author_Institution :
Dept. of Electron. Eng., Nat. Chiao Tung Univ., Hsinchu, Taiwan
Abstract :
The ANSI S1.11 1/3-octave filter bank is suitable for digital hearing aids, but its large group delay and high computational complexity complicate matters considerably. This study presents a 10-ms 18-band quasi-ANSI S1.11 1/3-octave filter bank for processing 24 kHz audio signals. We first discuss a filter order optimization algorithm to define the quasi-ANSI filters. The group delay constraint of filters is limited to 10 ms. The proposed design adopts an efficient prescription-fitting algorithm to reduce inter-band interference, enabling the proposed quasi-ANSI filter bank to compensate any type of hearing loss (HL) using the NAL-NL1 or HSE prescription formulas. Simulation results reveal that the maximum matching error in the prescriptions of the mild HL, moderate HL, and severe-to-profound HL is less than 1.5 dB. This study also investigates the complexity-effective multirate IFIR quasi-ANSI filter bank. For an 18-band digital hearing aid with a 24 kHz sampling rate, the proposed architecture eliminates approximately 93% of the multiplications and up to 74% of the storage elements, compared with a parallel FIR filters architecture. The proposed analysis filter bank (AFB) was designed in UMC 90 nm CMOS high-VT technology, and on the basis of post-layout simulations, it consumes 73 μW (@VDD=1 V). By voltage scaling (to 0.6 V), the simulation results show that the power consumption decreases to 27 μW, which is approximately 30% of that consumed by the most energy-efficient AFB available in the literature for use in hearing aids.
Keywords :
CMOS integrated circuits; FIR filters; audio signal processing; channel bank filters; computational complexity; delays; hearing aids; interference (signal); optimisation; pattern matching; power aware computing; signal sampling; 18-band digital hearing aid; HSE prescription formulas; NAL-NL1; UMC CMOS high-VT technology; analysis filter bank; audio signal processing; complexity-effective multirate IFIR quasiANSI filter bank; computational complexity; energy-efficient AFB; filter order optimization algorithm; group delay; group delay constraint; hearing loss; interband interference; matching error; mild HL; moderate HL; parallel FIR filters architecture; post-layout simulations; prescription-fitting algorithm; quasiANSI S1.11 1/3-octave filter bank; sampling rate; severe-to-profound HL; voltage scaling; Algorithm design and analysis; Auditory system; Bandwidth; Delay; Filter banks; Hearing aids; Standards; Filter bank; hearing aid; low group delay;
Journal_Title :
Circuits and Systems I: Regular Papers, IEEE Transactions on
DOI :
10.1109/TCSI.2012.2209731