Do baby-talk words reflect biomechanical constraints on speech production?

Baby-talk words are conventionalized lexical items used in infant-directed speech. According to the Frame/Content theory, the structure of baby-talk words reflects biomechanical constraints on speech production associated with the origin of speech, a hypothesis that yields three predictions — compared to adult vocabulary, baby-talk words should exhibit (1) more canonical CV syllables, (2) more intrasyllabic CV co-occurrence patterns that minimize tongue movement, and (3) a stronger preference for intersyllabic CVC patterns with labial-vowel-coronal, rather than coronal-vowel-labial, sequences. We tested these predictions in a corpus of 351 baby-talk words (e.g., choochoo) matched with their corresponding adult alternatives (e.g., train) in 10 languages. Although the results support the prediction related to canonical CV syllables, they fail to confirm the two predictions related to intrasyllabic and intersyllabic segmental sequences. Baby-talk words do not appear to be any more compliant with the proposed biomechanical constraints than adult words, except in having more canonical CV syllables.