Beschreibung:
<jats:p>Adult-directed conversational speech (ADS) is characterized by a high level of acoustic imprecision which should theoretically cause problems for infant language learning. Whether infant-directed speech (IDS) is clearer than ADS is disputed. However, differences in prosody [Fernald (1989)], utterance length [Cooper (1997)], and acoustic features [Bernstein Ratner (1984) and Malsheen (1980)] have been found. Such differences have the potential to assist children in decoding language input [Fernald (1985)]. In prior research, the child’s age and language ability appear to affect speech clarification [Bernstein Ratner (1996)]. This study examines whether vowel clarification is a function of the infants’ age. More than 75 mother-infant dyads are being followed from 7 months to 2 years of age. Data reported here are from 10 dyads whose data have been fully analyzed. Plots of the first and second formant values for vowels in words spoken in IDS and ADS were compared at 7 and 11 months of age. Vowels to 7-month-old infants appear to show less clarification than those to 11-month infants, although individual patterns of clarification are evident. This study analyzes whether such variability in vowel clarification affects the rate of early infant vocalizations prior to language production. [Work supported by NSF BCS074512.]</jats:p>