Prosody and focus in speech to infants and adults.

Two studies investigated adults use of prosodic emphasis to mark focused words in speech to infants and adults. In Experiment 1,18 mothers told a story to a 14-month-old infant and to an adult, using a picture book in which 6 target items were the focus of attention. Prosodic emphasis was measured both acoustically and subjectively In speech to infants, mothers consistently positioned focused words on exaggerated pitch peaks in utterance-final position, whereas in speech to adults prosodic emphasis was more variable. In Experiment 2,12 women taught another adult an assembly procedure involving familiar and novel terminology. In both studies, stressed words in adultdirected speech rarely coincided with pitch peaks. However, in infant-directed speech, mothers regularly used pitch prominence to convey primary stress. The use of exaggerated pitch peaks at the ends of utterances to mark focused words may facilitate speech processing for the infant. Research on features of early linguistic experiences that influence language acquisition has begun to explore the role of prosody in providing the infant with acoustic cues to linguistic structure in the speech waveform. Faced with the problem of discovering the linguistically relevant units in continuous