Child-directed speech in Ku Waru and Nungon (Papua New Guinea)

We present the state-of-the-art in current understanding of special features of child-directed speech (CDS) in the Papuan languages Ku Waru and Nungon, in the domains of phonology, lexicon, prosody, and morphosyntax. CDS in both languages features optional modification of consonants that makes them sound similar to early child productions, and Nungon CDS vowels are not hyper-articulated relative to vowels in adult-directed speech (ADS). Both languages are described by native speakers as utilizing a medium-sized set of special baby-talk lexical items, and these have variable distribution relative to ADS lexical counterparts in corpora. Nungon CDS has higher mean pitch and greater pitch range in CDS relative to ADS, while Ku Waru results are less conclusive in this direction. CDS in Nungon, but not as clearly in Ku Waru, shows evidence of morphosyntactic ‘fine-tuning’ to child production abilities. In Nungon, CDS features an unusual morphosyntactic alteration that arguably makes sentences longer and more syntactically complex, but simplifies words morphologically. Overall, the possible modifications available for CDS in both languages constitute less a coherent ‘register’ that speakers may slip into or out of, but more a menu of optional features, some apparently binary and some measured in terms of degree, which may be applied in conjunction with each other or separately, and which adults often apply variably within a single recording session.