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báo cáo hóa học:" Research Article Very Low Rate Scalable Speech Coding through Classified Embedded Matrix Quantization"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Very Low Rate Scalable Speech Coding through Classified Embedded Matrix Quantization | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2010 Article ID 480345 13 pages doi 10.1155 2010 480345 Research Article Very Low Rate Scalable Speech Coding through Classified Embedded Matrix Quantization Ehsan Jahangiri1 2 and Shahrokh Ghaemmaghami2 1 Department of Electrical Computer Engineering Johns Hopkins University Baltimore MD 21218 USA 2 Department of Electrical Engineering Sharif University of Technology P.O. Box 14588-89694 Tehran Iran Correspondence should be addressed to Ehsan Jahangiri jahangiri.ehsan@gmail.com Received 21 June 2009 Revised 2 February 2010 Accepted 19 February 2010 Academic Editor Soren Jensen Copyright 2010 E. Jahangiri and S. Ghaemmaghami. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. This paper proposes a scalable speech coding scheme using the embedded matrix quantization of the LSFs in the LPC model. For an efficient quantization of the spectral parameters two types of codebooks of different sizes are designed and used to encode unvoiced and mixed voicing segments separately. The tree-like structured codebooks of our embedded quantizer constructed through a cell merging process help to make a fine-grain scalable speech coder. Using an efficient adaptive dual-band approximation of the LPC excitation where voicing transition frequency is determined based on the concept of instantaneous frequency in the frequency domain near natural sounding synthesized speech is achieved. Assessment results including both overall quality and intelligibility scores show that the proposed coding scheme can be a reasonable choice for speech coding in low bandwidth communication applications. 1. Introduction Scalable speech coding refers to the coding schemes that reconstruct speech at different levels of accuracy or quality at various bit rates. The