Infant Sensitivity to Prosodic Variation
By: Oxford Academic
Tags: Prosody, Infant Learning, Oxford University Press, Linguistics, Language

This excerpt from The Oxford Handbook of Language Prosody, edited by Carlos Gussenhoven and Aoju Chen, is drawn from an article entitled “Development of phrase-level prosody from infancy to late childhood.” It explores the current research regarding infants’ ability to discern tonal patterns and rhythms in speech. This article and Handbook will be available on Oxford Handbooks Online in March 2021.

Infants are sensitive to prosodic variation within and across languages from birth. This sensitivity undergirds early perceptual attunement to ambient language patterns. Infant vocalizations incorporate prosody from a very early age. Whereas the earliest prosodic adaptations to social context may reflect links between acoustic vocal properties and emotional states, it is clear that infants also begin to incorporate language-specific patterns into their vocal repertoires before they begin to speak.

Infants are acutely sensitive to prosody from birth (see chapter 40). They can distinguish between rhythmically different languages shortly after birth and prefer to listen to a language that is rhythmically similar to their own at 3.5 to 5 months of age (Nazzi and Ramus 2003; Molnar et al. 2013). French newborns detect changes in pitch movement (rise vs. fall) in Japanese words (Nazzi et al. 1998b); English-listening 1- to 4-month-old infants can discriminate a pair of English words whose final vowels differ in pitch, duration, or intensity (Bull et al. 1984, 1985; Eilers et al. 1984). This sensitivity no doubt provides the foundation for the perception of tonal patterns (i.e. phonologically contrastive pitch patterns in a language).

This sensitivity no doubt provides the foundation for the perception of tonal patterns (i.e. phonologically contrastive pitch patterns in a language).

Research on early perception of tonal patterns has focused on infants’ perception of nonnative tonal patterns from a tone language (Tsao et al. 2004; Mattock and Burnham 2006; Yeung et al. 2013; Liu and Kager 2014; Singh and Fu 2016; see also chapter 38). The main finding is that infants’ tonal perception narrows in the first year of life, a phenomenon known as ‘phonological attunement’ or ‘perceptual reorganization’. Whereas all infants can discriminate most native and non-native patterns from birth to between 4 and 6 months of age, sensitivity to native tonal patterns is retained or enhanced after 6 months of age but sensitivity to non-native tonal patterns declines, albeit only in infants whose ambient language does not have lexical tone. Thus, perceptual attunement to tonal patterns is similar to that reported for vowels and consonants, though it occurs at a slightly earlier age (see Kuhl 2004; Saffran et al. 2006; Yeung et al. 2013).

Limited research on infants’ perception of native tonal categories in intonation languages shows that early tonal perception may be influenced by how consistently a tonal pattern occurs in a certain communication context and how salient acoustic differences between tonal patterns are (Soderstrom et al. 2011; Frota et al. 2014; Butler et al. 2016; see Frota and Butler 2018 for a review). For example, European Portuguese-learning infants can discriminate between nuclear contours with different boundary tones, such as fall and fall-rise, as early as 5 months of age (Frota et al. 2014), but English-learning infants aged 4 to 24 months do not easily discriminate between rising nuclear contours and non-rising nuclear contours (Soderstrom et al. 2011). Though not directly comparable due to methodological differences (e.g. one-word utterances with different nuclear contours presented in different blocks of stimuli in the Portuguese study vs. multiword utterances with different nuclear contours mixed in the same blocks of stimuli in the English study), the different findings provide initial evidence for infants’ sensitivity to the coupling between tonal patterns and communication contexts. In particular, falling nuclear contours are frequently used when making statements and fall-rise nuclear contours are frequently used when asking questions in European Portuguese, whereas rising and non-rising patterns are used in tandem in both situations in English (Soderstrom et al. 2011; Frota et al. 2014). More recently, Butler et al. (2016) have shown that European Portuguese-learning infants do not show sensitivity to contrasts in peak alignment (i.e. the difference between a pitch peak at the end of a stressed syllable vs. on the following syllable) until 8 to 12 months of age, even though these alignment contrasts consistently signal different focus types. Together, the studies on European Portuguese-learning infants suggest that infants acquire tonal contrasts with more salient acoustic differences (i.e. direction of final pitch movement) earlier than tonal contrasts with less salient acoustic differences (e.g. peak alignment) if there is little difference in how consistently a tonal pattern occurs in a certain communication context.

Research on early perception of prosodic phrasing suggests perceptual narrowing around boundary cues.

Research on early perception of prosodic phrasing suggests perceptual narrowing around boundary cues. Major prosodic boundaries, such as intonational phrase boundaries, are demarcated by several acoustic cues, including pre-boundary lengthening, pausing, and pitch changes (Ferreira 2007; Mo 2010; Wagner and Watson 2010; Holzgrefe-Lang et al. 2016; Zhang 2012). Languages differ in the distribution of these cues and so listeners weight them differently when identifying boundaries (Peters et al. 2005; Holzgrefe-Lang et al. 2016). For example, English- and Mandarin-speaking listeners treat pitch change as a more reliable cue to boundary perception than pre-boundary lengthening and pause, but Dutch-speaking listeners appear to treat pause as a more reliable cue to boundary perception than pitch changes and boundary tones (Sanderman and Collier 1997; Swerts 1997). As with tonal patterns, infants become attuned to language-specific boundary marking over developmental time. Between 4 and 6 months of age, infants exposed to different languages can discriminate well-formed and ill-formed prosodic units (e.g. ‘rabbits eat leafy vegetables’ spoken as one intonational phrase or as part of two different intonational phrases with a boundary between ‘eat’ and ‘leafy’) only if all boundary cues are present (Seidl and Cristià 2008; Wellmann et al. 2012); between 6 and 8 months of age, infants begin to rely only on those cues that adults find most critical for boundary marking (Seidl 2007; Johnson and Seidl 2008; Wellmann et al. 2012). To take another specific example, English-learning 6-month-old infants attend more to pitch changes than to the other cues at intonational phrase boundaries, but Dutch-learning 6-month-old infants attend more to pausing than to other cues at intonational phrase boundaries (Johnson and Seidl 2008).