SPEECH SYNTHESIS UNIT SELECTION

A method of selecting units for speech synthesis includes receiving, by one or more computers of a text-to-speech system, data indicating text for speech synthesis; determining, by the one or more computers, a sequence of text units that each represent a respective portion of the text, the sequence of text units including at least a first text unit followed by a second text unit; determining, by the one or more computers, multiple paths of speech units that each represent the sequence of text units, wherein determining the multiple paths of speech units includes: selecting, from a speech unit corpus, a first speech unit that includes speech synthesis data representing the first text unit; selecting, from the speech unit corpus, multiple second speech units including speech synthesis data representing the second text unit, each of the multiple second speech units being determined based on (i) a join cost to concatenate the second speech unit with a first speech unit and (ii) a target cost indicating a degree that the second speech unit corresponds to the second text unit; and defining paths from the selected first speech unit to each of the multiple second speech units to include in the multiple paths of speech units; and providing, by the one or more computers of the text-to-speech system, synthesized speech data according to a path selected from among the multiple paths.