1200 kbps MELP Coder with Codebook Driven Noisy Speech Enhancement

• Main Authors: Wei-Yi Tsai, 蔡維益
• Other Authors: 簡福榮
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/6sz839

碩士 === 國立臺北科技大學 === 電機工程系研究所 === 100 === The MELP speech coder operating in clean environment can provide fair communication quality, but suffers speech degradation while operating in noisy background environment. For most low bit-rate speech coders, the line spectrum pair (LSP) parameters are widely used to represent the spectral envelope of speech. And the accurate reconstruction of the spectral envelope is necessary. In the thesis, we proposed a codebook driven noisy speech enhancement scheme for the joint estimation of linear predictive coding (LPC) parameters of speech and noise from noisy observation. Maximum-likelihood estimates of the speech and noise LPC parameters are obtained by searching for the combination of codevectors that maximize the likelihood. Another two LSP encoding methods, the multistage vector quantizer(MSVQ) for single frame or superframe that is adopted by 2400 bps and 1200 bps mixed excitation linear prediction (MELP) coder, are included for comparison. Experimental results show that the proposed 2400 bps MELP coder performs slightly better than the proposed 1200 bps MELP coder. In addition, the proposed 2400 bps and 1200 bps MELP coders with codebook driven noisy speech enhancement all are superior to the standard 2400 bps and 1200 bps MELP coders.