1. A method comprising: selecting, via a processor, speech units from a speech unit database, where the speech units correspond to text; identifying a desired prosodic curve of speech produced from the speech units; identifying an actual prosodic curve of the speech units; modifying the speech units, to yield new speech units, such that a new prosodic curve corresponding to the new speech units matches the desired prosodic curve; and saving the new speech units to the speech unit database.