Comprehension of natural and synthetic speech using a sentence verification task

Abstract

A verification task was used to study sentence comprehension using two natural voices and five different synthetic voices generated by automatic text‐to‐speech conversion. Subjects listened to true and false, three‐ and six‐word sentence produced by one of these voices. Sentence verification accuracy and speed, and sentence transcription accuracy were measured. A significant effect of voice type was obtained for true and false sentences for all three measures. In addition, for false sentences, subjects were less accurate in transcribing six‐word sentences and they were slower in verifying these sentences. Furthermore, there were significant interactions of voice type with sentence length for all three dependent measures. Verification speed revealed a clustering of the seven voices into three basic categories corresponding to: (1) natural speech, (2) high‐quality synthetic speech, and (3) moderate‐ to low‐quality synthetic speech. Results from a second sentence verification task used to investigate effects of sentence predictability will also be discussed. [Work supported by AFOSR and NIH.]