The intelligibility and comprehension of synthetic versus natural speech in dyslexic students

Abstract

Introduction-Purpose: Despite the growing amount of data on the ‘synthetic speech perception’ by people with no disabilities, there has been limited research on the intelligibility and comprehension of synthetic speech systems by dyslexics. This study investigated the intelligibility and comprehension of synthetic versus natural speech in Greek dyslexic students.

Method: Forty three dyslexic students were presented with various acoustic stimuli (words, sentences, texts) both in synthetic and natural speech.

Results: The data analysis has shown that dyslexic students had identified better words and sentences presented in natural than in synthetic speech. In regards to their levels of performance in text comprehension there was not any significant difference between synthetic and natural speech. Perhaps their observed difficulties in their word/ sentence intelligibility did not manage to restrain their levels of text comprehensibility. It seemed as if the context cues provided by the text each time had assisted dyslexics in comprehending the text more effectively no matter the speech condition used (natural versus synthetic one).

Conclusion: Given that the overall purpose of reading is comprehension it is suggested that the text to speech systems could be used after all by the dyslexics as support as scaffolds for the intended purpose of reading comprehension.

Implications for rehabilitation

•  This research constitutes a trial to investigate the possibility of text-to-speech technology to serve as an educational aid for students with reading deficits helping them to master reading tasks that they may not have been able to do on their own. Students with reading disabilities need to be more successful in the reading process and managing at the same time to decrease the achievement gap that exists between them and those without disabilities. This work suggests that:

• • Text-to-speech technology needs further development and improvement to provide a closer to natural speech output in order to be a valuable educational aid for students with dyslexia.

• • Although there is a deviation, especially, in intelligibility between synthetic and natural speech that kind of assistive technology could provide a useful educational aid for those students that reading tasks appear to be a cumbersome process.

• • Natural and synthetic speech in combination and in discriminating use (for instance, natural speech in word tasks and synthetic in contextual tasks i.e., reading texts) could be integral tools to numerous educational settings and rehabilitation bodies.

Keywords:

• Intelligibility
• comprehension
• dyslexia
• synthetic speech
• natural speech
• TTS systems

Disclosure statement

No potential conflict of interest was reported by the authors.