6. A system comprising: a processor; and a computer-readable storage medium having instructions stored which, when executed by the processor, cause the processor to perform operations comprising: selecting speech units from a speech unit database, where the speech units are used to generate speech correspond to text; identifying a desired prosodic curve of the speech to be produced from the speech units; identifying an actual prosodic curve of the speech units; decomposing, via a residual-excited linear prediction algorithm, the speech units into residual coefficients and linear predictive coder coefficients; determining a cost of modifying the residual coefficients to yield a determination; modifying, via a pitch synchronous overlap and add algorithm, the residual coefficients, to yield modified residual coefficients based on the determination; combining, via the residual-excited linear prediction algorithm, the modified residual coefficients with the linear predictive coder coefficients, to yield new speech units, such that a new prosodic curve corresponding to the new speech units conforms to the desired prosodic curve; and generating the speech using the new speech units.
6. A system comprising: a processor; and a computer-readable storage medium having instructions stored which, when executed by the processor, cause the processor to perform operations comprising: selecting speech units from a speech unit database, where the speech units are used to generate speech correspond to text; identifying a desired prosodic curve of the speech to be produced from the speech units; identifying an actual prosodic curve of the speech units; decomposing, via a residual-excited linear prediction algorithm, the speech units into residual coefficients and linear predictive coder coefficients; determining a cost of modifying the residual coefficients to yield a determination; modifying, via a pitch synchronous overlap and add algorithm, the residual coefficients, to yield modified residual coefficients based on the determination; combining, via the residual-excited linear prediction algorithm, the modified residual coefficients with the linear predictive coder coefficients, to yield new speech units, such that a new prosodic curve corresponding to the new speech units conforms to the desired prosodic curve; and generating the speech using the new speech units. 9. The system of claim 6 , wherein the modifying of the residual coefficients comprises scaling a pitch of the residual coefficients.