Patent ID: 7035790

Claim:
A speech processing apparatus comprising: means for receiving 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 receiving means; a memory for storing data defining a predetermined function derived from a predetermined signal model which includes a first part having first parameters which models said source and a second part having second parameters which models said channel, said function being in terms of said first and second parameters and in terms of a set of speech signal values and generating, for a given set of received signal values, a probability density function which defines, for a given set of first and second parameters, the probability that the predetermined signal model has those parameter values, given that the signal is assumed to have generated the received set of signal values; means for applying said set of received signal values to said stored function; and means for processing said function with those values applied to obtain values of said first parameters that are representative of said speech generated by said speech source before it was distorted by said transmission channel.