Detail publikace

Abstrakt

The quality of speech produced by modern TTS systems utilizing the unit selection approach is very high. However, the system demands are enormous. The storage requirements are directly proportional to the size of speech unit inventory from which the units are selected during the synthesis process. This paper presents the analysis and reduction experiments performed on two large speech corpora employed by a unit selection TTS system for the Czech language. A procedure for exclusion of utterances from the default speech corpus based on statistics of the usage of particular speech units was proposed. The exclusion of whole utterances from the corpus was preferred over the exclusion of individual speech units in order to preserve the fundamental feature of the unit selection method - selection of possibly longest sequences of speech units. Experiments were performed for several reduction levels. Resulting synthetic speech was evaluated by a proposed statistics based on the concatenation points density. Moreover, the speech quality was evaluated in listening tests. All reduced versions of TTS system were evaluated as similar or slightly worse than the baseline system.