1. A computer-implemented method for concatenative speech synthesis comprising: accessing, using one or more computing devices, a plurality of speech synthesis units from a speech database; determining a similarity between the plurality of speech synthesis units, wherein determining the similarity is based upon, at least in part, a similarity factor; retrieving two or more speech synthesis units having the similarity; and pruning at least one of the two or more speech synthesis units based upon, at least in part, the similarity, wherein pruning is based upon, at least in part, a delta unit appearance frequency “DUAF” technique and wherein the DUAF is based upon, at least in part, a change in a unit appearance frequency and a change of the similarity factor.
1. A computer-implemented method for concatenative speech synthesis comprising: accessing, using one or more computing devices, a plurality of speech synthesis units from a speech database; determining a similarity between the plurality of speech synthesis units, wherein determining the similarity is based upon, at least in part, a similarity factor; retrieving two or more speech synthesis units having the similarity; and pruning at least one of the two or more speech synthesis units based upon, at least in part, the similarity, wherein pruning is based upon, at least in part, a delta unit appearance frequency “DUAF” technique and wherein the DUAF is based upon, at least in part, a change in a unit appearance frequency and a change of the similarity factor. 3. The method of claim 1 , further comprising: receiving a text input corresponding to an utterance during a massive synthesis phase associated with the concatenative speech synthesis.