10-ms 18-Band Quasi-ANSI S1.11 1/3-Octave Filter Bank for Digital Hearing Aids

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 W V). By voltage scaling (to 0.6 V), the simulation results show that the power consumption decreases to 27 W, which is approximately 30% of that consumed by the most energy-efficient AFB available in the literature for use in hearing aids.Index Terms-Filter bank, hearing aid, low group delay.

11.25-ms-Group-Delay and Low-Complexity Algorithm Design of 18-Band Quasi-ANSI S1.11 1/3 Octave Digital Filterbank for Hearing Aids

“…The cosine-modulated filterbank in the proposed structure can be calculated by a recursive discrete cosine transform (DCT) transform. The result shows that the proposed architecture is superior to Liu et al's structure [13] in terms of the computational complexity. Therefore, the proposed structure can achieve a less computational load for DSP operations in the future application.…”

“…To shorten the group delay, two quasi-ANSI S1.11 1/3-octave filterbanks [12], [13] are further proposed. However, the result of Liu et al [13] still caused a great number of multiplications, additions, and coefficients.…”

“…However, the result of Liu et al [13] still caused a great number of multiplications, additions, and coefficients. This implies that it is a very difficult trade-off between computational complexity and the cost of group delay.…”

A Reconfigurable Sound Wave Decomposition Filterbank for Hearing Aids Based on Nonlinear Transformation

“…For a certain set of can be firstly obtained by (3). Then based on and , the band edges of the masking filters and can be calculated by (13) and (14), respectively. In accordance with these specifications, the lengths of the subfilters are estimated by [21].…”

“…The multi-rate architecture saved both the power and chip size of hearing aids. A 10-ms 18-band Quasi-ANSI S1.11 1/3 octave filter bank was proposed in [14]. The inter-band interference was reduced by a prescription-fitting algorithm.…”