The classification of environmental sound events is of great significance for applications such as machine hearing and acoustic surveillance. Feature representation and feature vector dimension directly affect system performance. To better extract features and reduce computational burden, a novel frequency-energy feature representation and two-stage dimension reduction system were proposed. First, a frequency-energy diagram is generated. Based on this, the importance screening is done and only the energy bins of high importance are retained, which reduces the dimension of feature vector while extracting key information. Then the Bicubic interpolation method is used to further reduce the dimension. And the appropriate feature vector dimension is determined based on the change of information entropy. The proposed frequency-energy feature representation and two-stage dimension reduction system are evaluated with Real Word Computing Partnership sound scene database (RWCP-SSD), UrbanSound8K, and ESC-50 datasets, which demonstrate that the robustness is satisfactory under low signal-to-noise ratios (SNRs) and 15 noise types from NOISEX-92 database.

Filter banks with good reconfigurability are desired in hearing aid systems due to the individual requirements of patients with different hearing loss characteristics. This paper proposes a modularized design approach of a completely reconfigurable nonuniform filter bank for hearing aid systems. The proposed filter bank structure consists of a multiband generation module and a subband extraction module, where the frequency warping technique is adopted. Based on theoretical analyses of second order frequency warping, the subband distribution can be flexibly controlled. Moreover, to adapt the subband extraction module design to the multiband generation module, the relationship between control parameters is analyzed and a mapping formula is derived. Through the co-design of the two modules, superior reconfigurability over existing methods is achieved. Application examples show that the proposed filter bank is able to provide multiple subbands distribution schemes that satisfy the requirements of different audiograms. The proposed filter bank structure has lower complexity, smaller delay and smaller matching errors than existing filter bank structures due to its flexible structure.

In hearing aids system, adjustable filter bank is widely concerned because it can adapt to the matching requirement of audiograms with different characteristics. However, the adjustability of the existing filter banks is still not satisfactory. In this paper, a filter bank with improved adjustability based on Farrow structure was proposed. Both the bandwidths and central frequencies of the filter bank can be controlled flexibly. The experiment results show that the proposed filter bank has better compensation performance than current filter banks for hearing aids. In addition, the filter bank has low complexity. The delay is short enough to satisfy the requirement of the interaction between auditory and lip reading.

A non-uniformly spaced digital FIR filter bank has been proposed for QRS detection in wearable biomedical devices in Body Area Network (BAN) applications. The proposed filter bank is constructed based on frequency-response masking technique and employs two half-band filters as prototype filters, which leads to significant savings in terms of arithmetic operations. The introduction of non-uniformly spaced filter bank further enhances the detection accuracy especially in the BAN applications where motion artifacts are a major concern. Simulations show that the proposed algorithm correctly detects the QRS of both resting and exercising ECG, even under the presence of severe motion artifacts, baseline drift and large P/T waves.

In this paper, we proposed computationally efficient filter structures based on the frequency response masking (FRM) technique for the synthesis of arbitrary bandwidth sharp FIR filters. A two-step masking approach is introduced in the new structures to further reduce the arithmetic operations in the overall filter compared to original FRM structure. It was shown, by means of examples, that additional 12% to 17% savings in terms of numbers of arithmetic operations are achievable for the new structures.