Qinetiq Limited

Michael J Tomlinson

Keith M Ponting

Robert W Series

A recognition system ( ) incorporates a filterbank analyser ( ) producing successive data vectors of energy values for twenty-six frequency intervals in a speech signal. A unit ( ) compensates for spectral distortion in each vector. Compensated vectors undergo a transformation into feature vectors with twelve dimensions and are matched with hidden Markov model states in a computer ( ). Each matched model state has a mean value which is an estimate of the speech feature vector. A match inverter ( ) produces an estimate of the speech data vector in frequency space by a pseudo-inverse transformation. It includes information which will be lost in a later transformation to frequency space. The estimated data vector is compared with its associated speech signal data vector, and infinite impulse response filters ( ) average their difference with others. Averaged difference vectors so produced are used by the unit ( ) in compensation of speech signal data vectors.

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Malvern, United Kingdom

Michael J Tomlinson