Dynamic time warping using a digital signal processor

Abstract

A digital signal processor implementation of dynamic time warping for automatic speech recognition using a single memory array that stores only one sequence of accumulated correspondence values and detecting whether or not the constraint on horizontal path compression has been exceeded by storing negatives of calculated accumulated correspondence values to indicate horizontal path movement. The accumulated correspondence values are stored in the array in descending order; and memory locations of that array are reused as accumulated correspondence values are calculated representing the correspondence between a plurality of reference time frames and a plurality of unknown time frames representing an unknown word or utterance. When path movement is from an adjacent horizontal correspondence node to the present node, the negative of the calculated accumulated correspondence is written back into a memory location associated with the present node. When the accumulated correspondence associated with that memory location is calculated for the next sequence of accumulated correspondence values, the method detects the previously stored negative value and does not allow the path to move again in the horizontal direction.