According to Louise Robb (little over a decade ago):
“Studies of mother-infant interaction have, over the last twenty-five years, significantly altered our perception of infant capabilities, introducing concepts of innate capacities for perceiving human partners and their expressions, intersubjective motives regulating reciprocal communication and intersynchrony, and the key role of [-p.124] emotions and ‘affect attunement’ in early communication. Numerous studies have highlighted the reactive and co-operative role by means of which the infant enters into, and participates in, early communicative exchanges with caregivers. Communication is seen to play an essential role in the regulation of both cognitive and personality development in infancy. More recently, a surge of data has emerged identifying rhythm and predictable temporal organisation as an essential and fundamental aspect of early communication, which, in essence, is built upon salient musical features.” (pp.123-124)
“Pouthas (1996), confirming earlier theories… suggests that the infant’s ability to process time-related information, and a readiness to structure actions within time, are essential for developing perceptual and cognitive abilities, the learning of language, and the development of affective behaviour. Furthermore, the modulation of tempo by the mother and infant clearly has an important function in the regulation of emotions and the immediate emotional health of the infant.
The infant’s sensitivity to temporal and melodic variations in maternal behaviour from very early in the course of development explains the effects of disrupted communication. Experimental interference with the mother’s support of early interaction with her infant has demonstrated that interruption to the flow of her contingent and affectively supportive responses to what her child is doing can result in the infant showing distress and ceasing to smile, coo or emit prespeech utterances. It is to be expected, therefore, that the altered characteristics of expression in maternal postnatal depression may be accompanied by inappropriate timing of responses and disruption to the flow of communicative musicality, by which mutual and satisfying communication may be characterised.” (p.124)
“In healthy communication, a mother and infant enjoy interacting together in well-timed, reciprocal and rhythmically coordinated patterns that can be likened to a musical performance. Both partners show themselves to be highly sensitive to both the timing and quality of the emotional signals that are emitted in these communicative sequences – they create, together, what Trevarthen has described as an ’emotional narrative’ – the same concept as Daniel Stern’s ‘proto-narrative envelopes’.
Within these emotional narratives or ‘protoconversations’, it has been shown that the mother and the infant are sharing the beat and matching the rhythmic and melodic patterning of various time elements. The infant moves synchronously with the repetitive structure of the adult’s speech, in what has been termed ‘interactional synchrony’, and has been demonstrated that each is extremely sensitive to the durations of the other’s expressions on a moment-to-moment basis, making adjustments to their utterances and gestures. Thus, a mutually constructed activity level is created and maintained, each participant affirming how they should act together and take their turn. The degree of co-ordinated interpersonal timing [-p.126] achieved in these interactions has been shown to be associated with the level of infant engagement, the quality of affect and degree of closeness within the dyad. It also correlates with infant attachment, cognition and temperament at one year.” (pp.125-126)
“The baby talk register that is adopted by caregivers in communication with infants, is modified in distinctive ways in comparison with adult speech. These adjustments of parents’ talk to infants appear to be unconscious, and, in important ‘musical’ respects, are independent of the adult’s language, culture, sex and caregiving experience. The most notable and well-documented features include higher pitch, greater pitch range, elongated vowels, simple pitch contours, rhythmic regularity, slower tempo, briefer utterances, syntactic simplicity and overall repetitiveness. Research on lullabies suggests that infant-directed speech is comparable in many of its features to the more obviously musical characteristics of songs addressed to infants.” (p.126)
“…it is clear that the speech signal a mother addresses to her infant contains much more than textual information, and that the baby is responding communicatively to many subtle features. The infant’s reactions to musical qualities and contours in infant-directed speech, accompanying synchronous body movements, matching of time elements and mutual engagement on a shared beat display a subtle sense of rhythm . Malloch et al. (1997) describe this succession of ‘musically logical’ expressions between mother and infant as ‘communicative musicality’, which is said to characterise mutual and satisfying communication.” (p.127)
“…it appears that ‘satisfying’ communication involves regular and patterned events in time, and that important emotional information is carried in the quality of the voice by regulated features of pitch and loudness. In sum, the more ‘musical’ an exchange is, the more communicatively effective and conducive to infant self-regulation it will be.” (p.127)
“Research on the effects of low maternal mood and failure of a mother’s responses does show significant alterations and disturbances in the expression of emotion on [-p.128] both sides of the dyad.” (pp.127-128)
Ref: (italics in original; emphases in blue bold mine) Louise Robb (1999-2000) ‘Emotional musicality in mother-infant vocal affect, and an acoustic study of postnatal depression’ Musicae Scientiae Special Issue 1999-2000, pp.123-154
Abstract: “Mother-infant communication that satisfies both partners exhibits various musical elements. In cases where the mother is suffering from postnatal depression, qualities of rhythmic attunement, reciprocity and overall satisfaction with the interaction all decline. This case study reports detailed acoustic analysis of vocal interactions between a depressed mother and her infant at eight weeks and six months of age, and compares these with the same analysis of a healthy dyad at matching ages. Results showed the depressed mother to produce quieter, lower-pitched vocalisations, punctuated by longer pauses. Disruption was also evident in the depressed mother’s turn-taking behaviour. Matching of pitch, low arousal, less ‘joining in’ and negative mood states in the infant of the depressed mother suggested corresponding low affect in the baby. These characteristics of the depressed dyad’s communication improved as clinical symptoms declined. Both dyads showed periodicity in timing of interactions, but this was considerably slower and less co-ordinated in the depressed pair. The control dyad produced more evidence of reciprocal, happy communication with regular timing and ‘singing’ voice quality. These results present preliminary evidence of the importance of objectively defined features of communicative musicality in healthy, reciprocal interactions, and they highlight the part played by an innate pulse and shared timing within a musical framework in the organisation of the motives that regulate infant behaviours.” (italics in original, p.123)