17. A system, comprising: one or more processors; a memory that includes a plurality of computer-executable components, the plurality of computer-executable components comprising: a training module to refine a plurality of rich context models based on decision tree-tied Hidden Markov Models (HMMs) to produce a plurality of refined rich context models; a pre-selection module to perform pre-selection to compose a rich context model candidate sausage for an input text, the candidate sausage including a plurality of refined rich context model sequences, each sequence including at least some refined rich context models from the plurality of refined rich context models; a unit pruning module to implement unit pruning along the candidate sausage to select one or more rich context model sequences with less than a predetermined amount of distortion from a guiding sequence, the guiding sequence obtained from the decision tree-tied HMMs; a cross correlation search module to conduct a normalized cross correlation-based search to derive a minimal concatenation cost rich context model sequence from the one or more rich context model sequences; a waveform concatenation module to concatenate waveform units of an input text along a path of the minimal concatenation cost rich context model sequence to generate a waveform sequence; and a synthesis module to generate synthesized speech for the input text based at least on the waveform sequence.
17. A system, comprising: one or more processors; a memory that includes a plurality of computer-executable components, the plurality of computer-executable components comprising: a training module to refine a plurality of rich context models based on decision tree-tied Hidden Markov Models (HMMs) to produce a plurality of refined rich context models; a pre-selection module to perform pre-selection to compose a rich context model candidate sausage for an input text, the candidate sausage including a plurality of refined rich context model sequences, each sequence including at least some refined rich context models from the plurality of refined rich context models; a unit pruning module to implement unit pruning along the candidate sausage to select one or more rich context model sequences with less than a predetermined amount of distortion from a guiding sequence, the guiding sequence obtained from the decision tree-tied HMMs; a cross correlation search module to conduct a normalized cross correlation-based search to derive a minimal concatenation cost rich context model sequence from the one or more rich context model sequences; a waveform concatenation module to concatenate waveform units of an input text along a path of the minimal concatenation cost rich context model sequence to generate a waveform sequence; and a synthesis module to generate synthesized speech for the input text based at least on the waveform sequence. 18. The system of claim 17 , further comprising a data storage module to store the synthesized speech.