Some preliminary experiments in the recognition of connected digits

Abstract

A system is described for recognizing connected digits. The system is essentially speaker independent and has been programmed to recognize strings of three consecutive digits. In order to segment the input utterance into the single digits, a voiced-unvoiced-silence analysis is made using a pattern recognition algorithm. Based on both the voiced-unvoiced-silence contour, and variations in the energy contour of the utterance, a preliminary segmentation of the digit string is made. Boundary adjustments are then made based on a preliminary recognition of the individual digits. Finally a recognition algorithm, similar to the one used in the isolated digit recognition work described by Sambur and Rabiner, is used to classify the individual digits in the utterance. Experiments with the system using ten speakers (five male, five female) in a fairly low noise environment yielded a 91% correct digit recognition score. Similar experiments using ten new speakers (five male, five female) in a noisy computer room yielded an 87% correct digit recognition score.