On the Intelligibility of Fast Synthesized Speech for Individuals with Early-Onset Blindness

People with visual disabilities increasingly use text-to-speech synthesis as a primary output modality for interaction with computers. Surprisingly, there have been no systematic comparisons of the performance of different text-to-speech systems for this user population. In this paper we report the results of a pilot experiment on the intelligibility of fast synthesized speech for individuals with early-onset blindness. Using an open-response recall task, we collected data on four synthesis systems representing two major approaches to text-to-speech synthesis: formant-based synthesis and concatenative unit selection synthesis. We found a significant effect of speaking rate on intelligibility of synthesized speech, and a trend towards significance for synthesizer type. In post-hoc analyses, we found that participant-related factors, including age and familiarity with a synthesizer and voice, also affect intelligibility of fast synthesized speech.