Snižování paměťových nároků systému TTS pracujícího na principu výběru jednotek vyhozením promluv ze zdrojového řečového korpusu

Current unit selection speech synthesis systems are capable of producing speech of a high quality at the expense of enormous computational and storage requirements. In this paper, the analysis of an existing large speech corpus employed for unit-selection-based synthesis of Czech speech is performed. Subsequently, a procedure for the exclusion of some amount of utterances from the source speech corpus is proposed. The procedure is based on the statistics of the utilisation of all utterances during text-to-speech synthesis of a large portion of texts. The exclusion of whole utterances was preferred over the exclusion of the particular instances of speech units in order to preserve the main feature of unit selection framework - to select as longest sequence of contiguous speech units as possible. After the exclusion, the footprint of the system was reduced approximately by 42 %. The resulting synthetic speech was then judged by means of 5-scale CCR listening tests and evaluated in average as only "slightly worse" than speech generated by the baseline (i.e. not reduced) system