It is often assumed that pre-schoolers learn a second language (L2) with ease, even for structures that are absent in their L1, such as Mandarin-speaking pre-schoolers learning L2 English grammatical inflections (e.g., duck s , hors es ). However, while the results from Study 1 showed that such learners can imitate plural words (age = 3;5, N = 20), Studies 2 and 3 showed that they cannot yet generate or comprehend plural morphology (Study 2: age = 4;8, N = 20; Study 3: age = 4;1, N = 20), raising questions about when this is achieved. These findings have important implications for school readiness, as well as for identifying those at risk of developmental language disorders.

Learning to use word versus phrase level prosody to identify compounds from lists is thought to be a protracted process, only acquired by 11 years (Vogel & Raimy, 2002). However, a recent study has shown that 5-year-olds can use prosodic cues other than stress for these two structures in production, at least for early-acquired noun-noun compounds (Yuen et al., 2021). This raises the question of whether children this age can also use naturally-produced prosody to identify noun-noun compounds from their list forms in comprehension. The results show that 5-6-year-olds (N = 28) can only identify compounds. Unlike adults, children as a group could not use boundary cues to identify lists and were significantly slower in their processing compared to adults. This suggests that the acquisition of word level prosody may precede the acquisition of phrase level prosody, i.e., some higher-level aspects of phrasal prosody may take longer to acquire.

Although previous research has indicated that five-year-olds can use acoustic cues to disambiguate compounds (N1 + N2) from lists (N1, N2) (e.g., ‘ice-cream’ vs. ‘ice, cream’) (Yoshida & Katz, 2004, 2006), their productions are not yet fully adult-like (Wells, Peppé & Goulandris, 2004). The goal of this study was to examine this issue in Australian English-speaking children, with a focus on their use of F0, word duration, and pauses. Twenty-four five-year-olds and 20 adults participated in an elicited production experiment. Like adults, children produced distinct F0 patterns for the two structures. They also used longer word durations and more pauses in lists compared to compounds, indicating the presence of a boundary in lists. However, unlike adults, they also inappropriately inserted more pauses within the compound, suggesting the presence of a boundary in compounds as well. The implications for understanding children's developing knowledge of how to map acoustic cues to prosodic structures are discussed.

Subject–verb (SV) agreement helps listeners interpret the number condition of ambiguous nouns (The sheep is/are fat), yet it remains unclear whether young children use agreement to comprehend newly encountered nouns. Preschoolers and adults completed a forced choice task where sentences contained singular vs. plural copulas (Where is/are the [novel noun(s)]?). Novel nouns were either morphologically unambiguous (tup/tups) or ambiguous (/geks/ = singular: gex / plural: gecks). Preschoolers (and some adults) ignored the singular copula, interpreting /ks/-final words as plural, raising questions about the role of SV agreement in learners’ sentence comprehension and the status of is in Australian English.

Phonological processes can pose a learning challenge for children, where the surface form for an underlying contrast may vary as a function of the phonological environment. Mandarin tone sandhi is a complex phonological process that requires knowledge about both the tonal and the prosodic context in which it applies. The present study explored the productive knowledge of tone sandhi processes by 108 3- to 5-year-old Mandarin-speaking children and 33 adults. Participants were asked to produce novel tone sandhi compounds in different tonal contexts and prosodic structures. Acoustic analysis showed that 3-year-olds have abstracted the tone sandhi process and can productively apply it to novel disyllabic words across tonal contexts. However, even 5-year-olds still differed from adults in applying tone sandhi in response to the trisyllabic prosodic structure. The results are discussed in terms of the factors that influence how tone sandhi processes, and phonological alternations more generally, are acquired.

Weak syllables in Germanic and Romance languages have been reported to be challenging for young children, with syllable omission and/or incomplete reduction persisting till age five. In Mandarin Chinese, neutral tone (T0) involves a weak syllable with varied pitch realizations across (preceding) tonal contexts and short duration. The present study examined how and when T0 was acquired by 108 Beijing Mandarin-speaking children (3–5 years) relative to 33 adult controls. Lexicalized (familiar) and non-lexicalized (unfamiliar) T0 words were elicited in different preceding tonal contexts. Unlike previous reports, the present study revealed that children as young as three years have already developed a phonological category for T0, exhibiting contextually conditioned tonal realizations of T0 for both familiar and unfamiliar items. However, mastery of adult-like pitch and duration implementation of T0 is a protracted process not completed until age five. The implications for the acquisition of weak syllables more generally are discussed.

The readback/hearback loop is a communicative protocol used in many high-risk environments to ensure that a verbal instruction has been heard correctly by a receiver. However, it does not necessarily ensure that an instruction has been understood. Using an international sample of hydroelectric power generation controllers, this study examined whether particular linguistic (complete and partial readbacks) and prosodic (final intonation, filler, and interturn delay) cues contained within a readback response could signal to listeners the extent to which speakers had understood an instruction. The results indicated that different prosodic cues are used to detect nonunderstandings, depending upon the linguistic content of the readback. The results have implications for training and system design in distributed environments.

Two experiments focus on Thai tone perception by native speakers of tone languages (Thai, Cantonese, and Mandarin), a pitch–accent (Swedish), and a nontonal (English) language. In Experiment 1, there was better auditory-only and auditory–visual discrimination by tone and pitch–accent language speakers than by nontone language speakers. Conversely and counterintuitively, there was better visual-only discrimination by nontone language speakers than tone and pitch–accent language speakers. Nevertheless, visual augmentation of auditory tone perception in noise was evident for all five language groups. In Experiment 2, involving discrimination in three fundamental frequency equivalent auditory contexts, tone and pitch–accent language participants showed equivalent discrimination for normal Thai speech, filtered speech, and violin sounds. In contrast, nontone language listeners had significantly better discrimination for violin sounds than filtered speech and in turn speech. Together the results show that tone perception is determined by both auditory and visual information, by acoustic and linguistic contexts, and by universal and experiential factors.

Little is known about the acquisition of phonology in children learning a second language before the age of four. The study of Mandarin children's early learning of English coda consonants is of particular interest because of the different syllable structures permitted in the two languages. Using an elicited imitation task, this study explored the acquisition of coda consonants and related phrase-final lengthening in twelve three-year-old Mandarin-speaking children exposed to Australian English at preschool. Performance was good on /t/ and /s/ codas, but worse on the phonologically and morphologically more complex /ts/ coda. Although /n/ is one of the few codas permitted in Mandarin, both perceptual and acoustic analysis revealed surprisingly poor performance, suggesting possible L1 Mandarin effects. As expected, longer exposure to English resulted in better coda production. The results are discussed in terms of possible mechanisms underlying L2 phonological and morphological acquisition in early child second language learners (ECL2).