16. A tangible computer program product for evaluating naturalness of speech utterances by using crowd wisdom models, the tangible computer program product comprising: a non-transitory computer readable storage medium having computer readable program embodied therewith, the computer readable program comprising: computer readable program configured to present a plurality of human-testers with some of the obtained speech utterances; computer readable program configured to receive, for each presented speech utterance, a plurality of corresponding human testers generated speech utterances being human repetitions of the presented speech utterance; computer readable program configured to generate, for each presented speech utterance, an utterance-specific scoring model that is based on the corresponding human-tester generated speech utterances, each scoring model being configured to estimate a level of speech naturalness for the presented speech utterances using at least crowd wisdom models; computer readable program configured to update the scoring model for each presented speech utterance, based on respective human-tester generated speech utterances; and computer readable program configured to derive a speech naturalness score for each presented speech utterance by respectively applying the updated utterance-specific scoring model to each presented speech utterance.
16. A tangible computer program product for evaluating naturalness of speech utterances by using crowd wisdom models, the tangible computer program product comprising: a non-transitory computer readable storage medium having computer readable program embodied therewith, the computer readable program comprising: computer readable program configured to present a plurality of human-testers with some of the obtained speech utterances; computer readable program configured to receive, for each presented speech utterance, a plurality of corresponding human testers generated speech utterances being human repetitions of the presented speech utterance; computer readable program configured to generate, for each presented speech utterance, an utterance-specific scoring model that is based on the corresponding human-tester generated speech utterances, each scoring model being configured to estimate a level of speech naturalness for the presented speech utterances using at least crowd wisdom models; computer readable program configured to update the scoring model for each presented speech utterance, based on respective human-tester generated speech utterances; and computer readable program configured to derive a speech naturalness score for each presented speech utterance by respectively applying the updated utterance-specific scoring model to each presented speech utterance. 17. The tangible computer program product according to claim 16 , wherein the update of the scoring model is based on speech features extracted from the received speech utterances, and wherein each extracted feature contributes to the update of the scoring model in proportion to its cross-similarity among the received speech utterances.