Child-directed speech in noise: Listener- and environment-related changes in speech acoustics

Talkers adapt their speech in various ways according to the demands of their listeners and the communicative context. Mothers and their preschool children participated in a real-time interactive speech production/perception paradigm, in which mothers instructed their children (or an adult listener), to select the picture corresponding to the target word. The task was performed at low and high levels of background noise (56 and 76 dB SPL, delivered through headphones), to examine the effects of decreased audibility on speech production. Acoustic-phonetic analyses of child-directed speech (CDS) and adult-directed speech (ADS) productions of target words and carrier phrase (e.g., “Find pig” ), revealed that mothers significantly enhanced the suprasegmental properties (i.e., pitch, intensity, and duration) of target words in CDS and at higher noise levels, but provided limited evidence for the hyperarticulation of the segmental properties of speech (i.e., formant frequencies of vowels, or voice-onset times of stop consonants). Results suggest that while some aspects of articulatory control are readily amenable to change as function of task/listener demands, others may not be. Understanding these capacities and constraints in the talking caregiver is relevant to theories of hyperarticulation in infant-directed speech.