Journal of Beijing University of Posts and Telecommunications

  • EI核心期刊

JOURNAL OF BEIJING UNIVERSITY OF POSTS AND TELECOM ›› 2015, Vol. 38 ›› Issue (3): 28-33.doi: 10.13190/j.jbupt.2015.03.003

• Papers • Previous Articles     Next Articles

Vocoder Excitation Model Based on Voicing Cut-Off Frequency

XU Jing-yun1,2, ZHAO Xiao-qun1, LI Rong-yun1, WANG Qiao1   

  1. 1. School of Electronic and Information Engineering, Tongji University, Shanghai 201804, China;
    2. School of Engineering, Huzhou University, Zhejiang Huzhou 313000, China
  • Received:2014-11-08 Online:2015-06-28 Published:2015-06-26

Abstract:

A vocoder excitation model based on voicing cut-off frequency(VCO) was presented. In encoding part, the excitation spectrum was divided into two distinct spectral bands by VCO: harmonic sub-band and noise sub-band, the model of variable dimension through discrete cosine transform was used to express the excitation spectral parameter of harmonic sub-band, and VCO was quantized through 4bits nonlinear scalar quantization. In decoding part, the recovered excitation spectral parameter of harmonic sub-band was inversely Fourier transformed, the noise sub-band was obtained by the white noise pass through a high pass filter which used the VCO as the stop-band cut-off frequency, harmonic sub-band and noise sub-band were superimposed to get the excitation. The model greatly improves the description precision of the entire spectral envelope and harmonic plus noise components. With better subjective and objective indicators, especially for male's speech, the reconstructed speech shows more natural.

Key words: vocoder, harmonic plus noise excitation model, voicing cut-off frequency, discrete cosine transform

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