Comments on " Reducing Computation in Hmm Evaluation " Chen, " Low-bit-rate Predictive Coding of Speech Waveforms Based on Vector Quantization, "

Carl Mitchell, Mary Harper, and Leah Jamieson signal consists of a periodic signal and additive noise, the periodicity of the reconstructed signal increases. This likely is relevant for background noise. If the pitch-cycle waveform evolves slowly, i.e., if the changes from pitch cycle to pitch cycle are correlated, then the periodicity of the reconstructed signal is reduced. The latter situation may be applicable for voicing onsets and transitions. In a practical speech coder, other effects, such as the frequency dependence of the periodicity and the stepwise changes in the pitch period, also play a role in the periodicity of the reconstructed signal.