Natural and synthetic speech comprehension: comparison of children from two age groups

This study compared the ability of children from two age groups (6–7 and 9–11) to comprehend natural speech and DECTalk™ synthetic speech by using a sentence verification task. The effect of a short amount of listening practice on subjects' ability to comprehend both types of speech was investigated by comparing response latencies at two listening times spaced between 3 and 7 days apart. Mean language and nonverbal intelligence scores of the groups did not differ significantly. Natural speech response latencies did not shorten significantly from time 1 to time 2 for either group. Synthetic speech response latencies shortened significantly from time 1 to time 2 for the younger children only. Despite this significant effect of time for synthetic sentences for the younger children, both younger and older children responded significantly more slowly to synthetic than to natural speech at both times 1 and 2. The implications that these findings might have for children who use augmentative and alternative communication devices are discussed.