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Design of a Robust LSP Quantizer for a High-Quality 4-kbit/s CELP Speech Coder
Yusuke HIWASAKI Kazunori MANO Kazutoshi YASUNAGA Toshiyuki MORII Hiroyuki EHARA Takao KANEKO
IEICE TRANSACTIONS on Information and Systems
Publication Date: 2004/06/01
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Speech and Hearing
speech coding, spectral quantization, line spectrum pairs, line spectral frequencies, split vector quantization,
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This paper presents an efficient LSP quantizer implementation for low bit-rate coders. The major feature of the quantizer is that it uses a truncated cepstral distance criterion for the code selection procedure. This approach has generally been considered too computationally costly. We utilized the quantizer with a moving-average predictor, two-stage-split vector quantizer and delayed decision. We have investigated the optimal parameter settings in this case and incorporated the quantizer thus obtained into an ITU-T 4-kbit/s speech coding candidate algorithm with a bit budget of 21 bits. The objective performance is better than that with a conventional weighted mean-square criterion, while the complexity is still kept to a reasonable level. The paper also describes the codebook design and techniques that were employed to achieve robustness in noisy channel conditions.