5. The method according to claim 1 , wherein, the presenting and the receiving is preformed over a user interface providing specified incentives to the human testers in return to their repetitions of the respective presented speech utterances.
5. The method according to claim 1 , wherein, the presenting and the receiving is preformed over a user interface providing specified incentives to the human testers in return to their repetitions of the respective presented speech utterances. 9. The method according to claim 5 , wherein at least one of the incentives comprise: a speech naturalness score of a specified human tester, a speech naturalness score of a specified human tester in view of the scores of other human testers, and a similarity mapping of at least some of the human testers based on their relative similarity scores and their similarity score to a specified human tester, wherein the similarity mapping is presented graphically and in view of metadata information associated with the human testers.