Evaluation of synthetic speech

Abstract

Two paragraphs of computer-generated speech, with the same text, one made at Bell Laboratories by concatenating words spoken in isolation and the other at Haskins Laboratories using a phonetic dictionary, were evaluated with respect to the ease with which listeners could comprehend and retain information about the paragraph. A paragraph with the same text was recorded by a human speaker and used as a reference for comparison. Different groups of subjects listened to one of these three versions, hearing it one, two, or three times, and then answered questions concerning the content of the paragraph. The results indicate that for all three types of speech, comprehension measured in this way increased as a function of the number of times the paragraph was heard. The data indicated that there is a significant comprehensible difference between the two synthetic speech types. Scores for the speech generated by concatenating words spoken in isolation were closer to those for natural speech than were the scores obtained for speech synthesized from a phonetic dictionary.