Use of clustering information for coarticulation compensation in speech synthesis by word concatenation

The Weather Report Synthesizer is a speech synthesis system for weather forecasts in Greek. Instead of trying to improve the synthesis quality of PSOLA based diphone concatenation speech synthesizers, we have chosen to use words as the synthesis units. This approach has the advantage of low complexity and quick implementation, while at the same time it achieves better speech quality due to the fact that the synthesis units inherently possess the necessary prosodic feature diversity. The selection of the optimal sequence of words that form the synthesized speech, however, presents the greatest challenge in the synthesis process. Several features are taken into consideration during the selection, but we have identified Coarticulation at the edges of consecutive words to have the greatest effect on the quality of the synthesized utterance. We present a novel method for evaluating a measure on coarticulation effects among pairs of words, based on feature clustering information obtained from a current Speech Recognition System.