8. 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: receiving text as part of a text-to-speech process; selecting a speech segment associated with the text, wherein the speech segment is selected from a primary speech database which has been modified by: identifying primary speech segments in the primary speech database which do not meet a need of the text-to-speech process, wherein the primary speech segments comprise one of half-phones, half-phonemes, demi-syllables, and polyphones; identifying replacement speech segments which satisfy the need in a secondary speech database; and enhancing the primary speech database by substituting, in the primary database, the primary speech segments with the replacement speech segments; and generating speech corresponding to the text using the speech segment.
8. 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: receiving text as part of a text-to-speech process; selecting a speech segment associated with the text, wherein the speech segment is selected from a primary speech database which has been modified by: identifying primary speech segments in the primary speech database which do not meet a need of the text-to-speech process, wherein the primary speech segments comprise one of half-phones, half-phonemes, demi-syllables, and polyphones; identifying replacement speech segments which satisfy the need in a secondary speech database; and enhancing the primary speech database by substituting, in the primary database, the primary speech segments with the replacement speech segments; and generating speech corresponding to the text using the speech segment. 10. The system of claim 8 , wherein the primary speech segments are one of diphones, triphones, and phonemes.