1. A method of performing hybrid text-to-speech processing, the method comprising: receiving text data; determining a sequence of linguistic units corresponding to the text data, the sequence of linguistic units comprising a first linguistic unit and a second linguistic unit; determining to use a first parametric speech synthesis technique for the first linguistic unit, wherein the first parametric speech synthesis technique comprises synthesizing speech using a computerized voice generator; generating a representation of the first linguistic unit using a model for the first linguistic unit and using the first parametric speech synthesis technique; determining to use a unit selection speech synthesis technique for the second linguistic unit; retrieving a pre-recorded speech unit for the second linguistic unit from a unit selection database, wherein the pre-recorded speech unit comprises recorded speech that has been processed with an encoder and a decoder prior to storage in the unit selection database, to configure the pre-recorded speech unit with acoustic properties consistent with speech generated by the first parametric speech synthesis technique; concatenating the representation of the first linguistic unit and the pre-recorded speech unit to generate audio data; and causing audio corresponding to the audio data to be output using an audio speaker.