15. A method for creating context dependent synthesis units of a text-to-speech system, the method comprising the steps of: storing input speech from a target speaker and corresponding phonetic symbols of the input speech; identifying each unique context-dependent phoneme-based unit of the input speech, wherein a central phoneme-based unit is selected from a group consisting of a phoneme and a diphone; training a Hidden Markov Model (HMM) for each unique context-dependent phoneme-based unit based on context of at least one immediately preceding and succeeding phoneme-based units; clustering the HMMs into groups having the same central phoneme-based unit that sound similar but have different preceding or succeeding phoneme-based units; and selecting a context-dependent phoneme-based unit of each group to represent the corresponding group.
15. A method for creating context dependent synthesis units of a text-to-speech system, the method comprising the steps of: storing input speech from a target speaker and corresponding phonetic symbols of the input speech; identifying each unique context-dependent phoneme-based unit of the input speech, wherein a central phoneme-based unit is selected from a group consisting of a phoneme and a diphone; training a Hidden Markov Model (HMM) for each unique context-dependent phoneme-based unit based on context of at least one immediately preceding and succeeding phoneme-based units; clustering the HMMs into groups having the same central phoneme-based unit that sound similar but have different preceding or succeeding phoneme-based units; and selecting a context-dependent phoneme-based unit of each group to represent the corresponding group. 16. The method of claim 15 wherein the step of selecting includes selecting at least two context-dependent phoneme-based units to represent at least one of the groups.