| 摘要 |
A speech processing system is provided which is operable to receive sets of signal values representative of a speech signal generated by a speech source. The system is operable to determine a measure of the quality of the speech signal by performing a statistical analysis, in unit 21, of the received sets of signal values. The system stores, in memory 47, data defining a predetermined function derived from a signal model which models the speech source and which defines a probability density function which gives, for a given set of model parameters, the probability that the signal model has those model parameters given that the signal model is assumed to have generated the received set of signal values. The system applies a current set of received signal values to the stored probability density function and then draws samples of parameters values from it, e.g. using a Gibbs sampler 41. The system then analyses the samples to determine a measure of the variance of some of the samples and then outputs a signal indicative of the quality of the received speech signal values in dependence upon the determined variance. The parameter(s) sampled may include auto-regressive coefficients, moving average filter coefficients and process noise. The system may be used in speech encoding, transmission or recognition. Application to annotating and retrieving data files is described. |
