A Novel Subband Fractional Delay Algorithm Based on the Filterbank of Cochlear Implant [post]

Yan Chen, Yousheng Chen
2020 unpublished
Background: In recent years, microphone array method is gradually applied to speech enhancement of cochlear implant, and the delay parameter is the main parameter of microphone array beamforming technology. Due to the size limitation of cochlear implant, the microphone spacing is very small. In algorithm implementation, delay parameter usually corresponds to fractional sampling point. It is necessary to use fractional delay filter to realize the interpolation of integer sampling points. The
more » ... itional fractional delay method is to interpolate sampling points in the whole frequency band of speech. However, the speech frequency band itself is very wide, so the error of the present fractional delay method in cochlear is still large. Methods: We propose a fractional delay algorithm based on the filter bank of cochlear implant. The algorithm deduces and calculates the mathematical expression of the fractional delay filter of each subband, and forms a full band fractional delay filter algorithm to minimize the delay error of the whole band. Realization and results: Through the analysis of the system response curve and the calculation of the delay error, it can be seen that the system response corresponding to the fractional delay of each subband in the cochlear filter bank has only a small deviation from the ideal fractional delay filter. Therefore, the error of the fractional delay filter designed in this paper is very small, which can meet the requirements of cochlear implant using microphone array technology for the precision of delay parameters. Discussions: In this paper, the implementation algorithm of subband fractional delay filter is applied to signal acquisition of cochlear implant. Considering the space condition and delay parameters in the actual application scenario, the value of fractional delay can be any continuous real number between 0 and 3, and the error situation of the algorithm can be calculated and analyzed in this range. If the algorithm is extended to other applications, the numerical range of fractional delay can be extended. From the statistics of the average error, it can be seen that the average error of the proposed algorithm in the whole frequency band is extremely small, which can meet the needs of the accuracy of the delay parameters in the application of cochlear implant. Conclusions: The proposed fractional delay filter based on the minimum subband error of cochlear implant can not only realize the local fractional delay minimization, but also the error minimization of the whole frequency band.
doi:10.21203/rs.3.rs-21519/v1 fatcat:cw6r2gvkzjca7f7eungaalmpei