The paper describes the optimisation of Viterbi search used in unit selection TTS, since with a large speech corpus necessary to achieve a high level of naturalness, the performace still suffers. To improve the search speed, the combination of sophisticated stopping schemes and pruning thresholds is employed into the baseline search. The optimised search is, moreover, extremely flexible in configuration, requiring only three intuitively comprehensible coefficients to be set. This provides the means for tuning the search depending on device resources, while it allows reaching significant performance increase. To illustrate it, several configuration scenarios, with speed--up ranging from 6 to 58 times, are presented. Their impact on speech quality is verified by CCR listening test, taking into account only the phrases with the highest number of differences when compared to the baseline search.
Bibliographic reference. Tihelka, Daniel / Kala, Jiří / Matoušek, Jindřich (2010): "Enhancements of viterbi search for fast unit selection synthesis", In INTERSPEECH-2010, 174-177.