From melody to words: vocal development in human infants

The human infant is the most proficient vocal learner, and differs from his primate relatives in that he is specifically pre-adapted to acquire oral language. Melody (fundamental frequency contour) is a key entity to understand early language development. Infants from all cultures seem to pass through the same early stages of melody development at the same phase of their life history, long before vocabulary and grammar are established. Vocal development starts with an increasing complexification of melody over the first few months of life. The presentation will demonstrate what we mean by complexification of cry melody, how complex melodies are composed and modified, and why melody development marks crucial stages of early language acquisition. Along with adolescence, the neonatal period is a time when hormones may contribute to long-lasting, sexually dimorphic patterns of behavioural performance. This postnatal period of elevated hormone levels in both sexes is known as ‘mini-puberty”. The transitory surge of sex steroids within the first months of life is associated with dramatic developing brain changes, as well as the start of language-relevant vocal development in human infants. Recently, a significant positive association between mini-pubertal estradiol surges and early vocal performances (cry melody pattern, articulatory skills in babbling) has been demonstrated. This could bridge infant research to research in song birds, whose song learning has been postulated as modelling babbling in human infants