Duration Modeling in Mandarin Connected Digit Recognition

Digit string recognition is required in many applications which need to recognize numbers such as telephone numbers, credit card numbers, date, etc. In order to design a high performance recognizer, duration information is explored in this study. In a Mandarin connected digit recognizer, insertion and deletion errors amount to more than two thirds of the total recognition errors because there exist two mono-phonemic digits and a heavily rhotacized vowel. In order to use duration information more efficiently, we propose a method to model context dependent word duration information and then incorporate it directly in the decoding algorithm. Experimental results show that this method reduces word error rate by as much as 32.1%.