Patent ID: 7010483
Filing Date: 2006-03-07
Classification: G10L

Abstract:
1. An apparatus for determining a quality measure indicative of the quality of a speech signal, the apparatus comprising: a receiver operable to receive a set of speech signal values representative of a speech signal generated by a speech source as distorted by a transmission channel between the speech source and the receiver; a memory operable to store a predetermined function which includes a first part having first parameters which models said source and a second part having second parameters which models said channel and which gives, for a given set of speech signal values, a probability density for parameters of a predetermined speech model which is assumed to have generated the set of speech signal values, the probability density defining, for a given set of model parameter values, the probability that the predetermined speech model has those parameter values, given that the model is assumed to have generated the set of speech signal values; an applicator operable to apply the set of received speech signal values to said stored function to give the probability density for said model parameters for the set of received speech signal values; a processor operable to process said function with said set of received speech signal values applied, to derive samples of at least said first parameters from said probability density; an analyser operable to analyse at least some of said derived samples of said at least first parameters to determine a quality measure indicative of the quality of the received speech signal values; and an output operable to output values of said first parameters that are representative of said speech signal generated by said speech source before it was distorted by said transmission channel.