DECtalk™ and VeriVox™: Intelligibility, Likeability, and Rate Preference Differences for Four Listener Groups

The intelligibility, likeability, and speech presentation rates for two types of popular synthesized speech, DECtalk™ and VeriVox™, were investigated across four age groups ranging from 6–85 years old. Results for all age groups revealed differences in intelligibility between synthesized adult and child voices, with intelligibility scores for child synthesized voices significantly below those for adult synthesized voices. The most popular synthesized voices were from the VeriVox family. Of interest is that preferred speech presentation rate, expressed as mean words per minute, increased as a function of age, with the oldest listeners preferring the fastest speech presentation rate. This is inconsistent with previous studies that have investigated rate preferences among older adults, and could reflect the different synthesized speech options employed in this study. Implications of these findings for the improvement of text-to-speech products and the practice of AAC are discussed, along with suggestions for further research.

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