Psytechnics Limited

Ludovic Malfait

Philip Gray

Benjamin Pernot

Paul Barrett

This invention relates to alignment of signals, particularly for use in a quality assessment system. The invention provides a method and apparatus for aligning a first signal comprising a sequence of frames with a second signal comprising a sequence of frames, the method comprising the steps of: determining a similarity measure between each of a plurality of frames of the first signal and each of a plurality of frames of the second signal; assigning a matching value to each frame of the first signal wherein the matching value indicates a relative position of a matching frame in the second signal, by repeating the sub-steps of: generating a relative delay histogram the histogram comprising a set of values corresponding to each of a set of relative delays by: selecting a subset of frames of the first signal and for each frame of said subset identifying the frame of the second signal having the greatest similarity with said frame; determining the relative delay between the identified frame of the second signal and said frame of the first signal; and incrementing the value of the histogram corresponding to said relative delay; identifying one or more peaks in the relative delay histogram; and assigning the matching value to each frame contributing to a peak in dependence upon said identified peaks.

Method and apparatus for aligning signals

A non-intrusive speech quality assessment system. A method and apparatus for training a quality assessment tool in which a database comprising a plurality of samples, each with an associated mean opinion score, is divided into a plurality of distortion sets of samples according to a distortion criterion; and a distortion specific assessment handler for each distortion set is trained, such that a fit between a distortion specific quality measure generated from a distortion specific plurality of parameters for a sample and the mean opinion score associated with said sample is optimised. A method and apparatus for assessing speech quality in a telecommunications network in which a dominant distortion type is determined for a sample; a distortion specific plurality of parameters are combined to provide a distortion specific quality measure for each sample; and a quality measure is generated in dependence upon the distortion specific quality measure.

Quality assessment tool

This invention relates to a new parameter suitable for use in non-intrusive speech quality assessment system. The invention provides a method of generating a parameter from a signal comprising a sequence of values measured from voiced portions of said signal at a sampling frequency, said parameter suitable for use in a quality assessment tool. The method includes steps of selecting portions of frequency transformed sections of the signal in dependence upon a pitch estimate; generating an average value for each portion; and generating a section parameter depending upon the difference between the averages of successive portions. Said section parameter is averaged over a number of iterations of the method to generate the new parameter of the invention.

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Ipswich, United Kingdom

Ludovic Malfait