Developmental Differences in Infant Attention to the Spectral Properties of Infant-Directed Speech

Abstract

Across several independent studies, infants from a few days to 9 months of age have shown preferences for infant-directed (ID) over adult-directed (AD) speech. Moreover, 4-month-olds have been shown to prefer sine-wave analogs of the fundamental frequency of ID speech, suggesting that exaggerated pitch contours are prepotent stimuli for infants. The possibility of similar preferences by 1-month-olds was examined in a series of experiments, using a fixation-based preference procedure. Results from the first 2 experiments showed that 1-month-olds did not prefer the lower-frequency pitch characteristics of ID speech, even though 1-month-olds were able to discriminate low-pass filtered ID and AD speech. Since low-pass filtering may have distorted the fundamental frequency characteristics of ID speech, 1-month-olds were also tested with sine-wave analogs of the fundamental frequencies of the ID utterances. Infants in this third experiment also showed no preference for ID pitch contours. In the fourth experiment, 1-month-olds preferred a natural recording of ID speech over a version which preserved only its lower frequency prosodic features. From these results, it is argued that, although young infants are similar to older infants in their attraction to ID speech, their preferences depend on a wider range of acoustic features (e.g., spectral structure). It is suggested that exaggerated pitch contours which characterize ID speech may become salient communicative signals for infants through language-rich, interactive experiences with caretakers and increased perceptual acuity over the first months after birth.

Foreign-language experience in infancy: Effects of short-term exposure and social interaction on phonetic learning

“…The findings show that reversing the decline does not require long-term listening to the foreign language. The components critical to learning in the live situation of Experiment 1 likely include: (i) infant-directed speech (24,25), a speech pattern that has been shown to attract and hold infant attention (27,28); (ii) the use of multiple talkers, which increases variability in the acoustic cues to phonetic categories and results in better phonetic learning in adult listeners mastering a foreign language (37); and (iii) phonetic units whose acoustic cues are exaggerated, making them more distinct (29). The exaggeration of phonetic units by parents has been shown to be strongly associated with enhanced phonetic perception in infants (26); exaggeration is also reported to improve phonetic perception in children with dyslexia (38,39).…”

“…The speakers used infant-directed speech, or ''motherese'' (24)(25)(26), which infants prefer when given a choice (27,28). Infant-directed speech has a higher pitch, extended intonation contours, and exaggerated phonetic cues (29).…”

A connectionist study on the role of pitch in infant-directed speech

“…1,2 At the most basic level, the exaggerated prosody of IDS seems to obtain and maintain infants' attention. 9 When presented with IDS versus ADS utterances, sleeping neonates show increased cerebral blood flow for IDS, 10 four-month-olds show differential habituation responses, 11 and infants listen longer to IDS than ADS. 12 Besides attention, IDS is believed to foster affective, cognitive and social development, for example, by supporting emotional exchanges, 13,14 transmitting communicative intentions, 15 synchronizing mother-infant dyadic interactions, 16 and promoting voice-face associative learning.…”

Infants' Listening Preferences: Baby Talk or Happy Talk?

“…As early as the first month of life, infants prefer to listen to speech rather than nonspeech (Cooper & Aslin, 1994), mothers' speech rather than other females' speech (DeCasper…”