Synthesized speech intelligibility among native speakers and non-native speakers of English.

Using synthesized and digitized speech in electronic communication devices may greatly benefit individuals who cannot produce intelligible speech. However, multiple investigations have demonstrated that synthesized speech is not always sufficiently intelligible for its listeners. Listening to synthesized speech may be particularly problematic for listeners for whom English is a second language. We compared native and non-native English-speaking adults' listening accuracy for English sentences in natural voice and synthesized voice conditions. Results indicated a disproportionate disadvantage for the non-native English-speaking group when listening to synthesized speech compared to their native English-speaking age peers. There was, however, significant variability in performance within the non-native English group, and this was strongly related to independent measures of English language skill. Specifically, a large portion of the variance in performance on the synthesized speech task was predicted by participants' receptive vocabulary scores.