Signal modification incorporating perceptual weighting filter
Joon‐Hyuk Chang, Woohyung Lim, Nam Soo Kim · 2006
Abstract In this paper, an improved preprocessor for low-bit-rate speech coding employing the perceptual weightingfilter is proposed. Speech modification in the proposedapproach is performed according to a criterion whichmakes a compromise between the modification and per-ceptual weighted quantization errors. For this, the per-ceptual weighting filter is expressed in terms of a trans-form domain matrix. The proposed approach is effec-tive in enhancing the speech signal at coder-decoder(CODEC) output through a number of listening tests. 1. Introduction Ingeneral,theperformanceofalow-bit-ratespeechcoderdegrades seriously under the presence of various inter-fering signals such as background noise, acoustic echo,music sounds or interfering speaker’s speech. This phe-nomenon is mainly due to the deviation from the as-sumed speech production model which is used in thecodebook training since a number of codebooks used inthe coder are trained based on a large amount of speechdata and the ranges for parameter search are specified tofit the pure speech signals. One of the successful appli-cations of the unwanted distortion reduction technique tolow-bit-rate coding is the speech enhancement technique[2, 3, 8, 1]. Even though aforementioned enhancementtechniques have been found effective in the presence of astationary background noise, they are not capable of han-dling such interfering signals as the acoustic echoes, mu-sicsoundsorco-talkers’speech. Thisismainlyduetothefactthattheconventionalapproachesadopttheopenloopanalysis which can not take advantage of speech codercharacteristics. An alternative method is the generalized