Wavelet analysis based multiband excited vocoder

The multiband excitation (MBE) vocoder is a high quality and low complexity speech coder, which is a pitch sensitive speech coder. The authors present a new pitch period estimation method, which is based an wavelet analysis theory. In this method each frame of speech is processed by wavelet transform (WT), then the pitch period is estimated in the frequency domain by a rational interpolation. The results of experiments show that the accuracy of the pitch period can reach the 1/16 sample point and that the method suits different speakers. Computation in this method is time saving and easy to apply in real time implementation. The authors also present improved algorithms for decisions on parameters of the spectrum envelope A/sub m/ and voiced/unvoiced V/UV decision. Based on this, they completed a 4.2 kbps MBE vocoder by computer simulation. The results show that this MBE vocoder is better than the normal transform vocoder both in speech quality and complexity, and easy to realize on a single DSP chip TMS320C25.<>