METHOD FOR ESTIMATING A CONFIDENCE MEASURE FOR A SPEECH RECOGNITION SYSTEM

A method of estimating a confidence measure for a speech recognition system, involves comparing an input speech signal with a number of predetermined models of possible speech signals. Best scores indicating the degree of similarity between the input speech signal and each of the predetermined models are then used to determine a normalized variance, which is used as the Confidence Measure, in order to determine whether the input speech signal has been correctly recognized, the Confidence Measure is compared to a threshold value. The threshold value is weighted according to the Signal to Noise Ratio of the input speech signal and according to the number of predetermined models used.