There is a long-standing debate in the literature about the benefits that acoustic components of Infant Directed Speech (IDS) might have for infants' language acquisition. One of the highly contested features is vowel space expansion, which refers to the enlargement of the acoustic space between the corner vowels /i, u, a/ in IDS compared to Adult…

Research on the acoustic characteristics of Infant Directed Speech (IDS) in North American English indicates that it is generally higher-pitched than Adult Directed Speech (ADS) and has unique prosodic characteristics, which is commonly found across many spoken languages. However, very little research has addressed another important aspect of…

Infant-directed speech (IDS) is characterized by a range of register-typical characteristics. Many of those can be objectively measured, such as acoustic-prosodic and structural-linguistic modifications. Perceived vocal affect, however, is a socio-emotional IDS characteristic and is subjectively assessed. Vocal affect goes beyond acoustic-prosodic…

Non-tone language infants' native language recognition is based first on supra-segmental then segmental cues, but this trajectory is unknown for tone-language infants. This study investigated non-tone (English) and tone (Thai) language 6- to 10-month-old infants' preference for English vs. Thai one-syllable words (containing segmental and tone…

Onomatopoeia are disproportionately high in number in infants' early words compared to adult language. Studies of infant language perception have proposed an iconic advantage for onomatopoeia, which may make them easier for infants to learn. This study analyses infants' early word production to show a phonological motivation for onomatopoeia in…

One of the first challenges facing the young language learner is the task of segmenting words from a natural language speech stream, without prior knowledge of how these words sound. Studies with younger children find that children find it easier to segment words from fluent speech when the words are presented in infant-directed speech, i.e., the…

Infants perceive intonation contrasts early in development in contrast to lexical stress but similarly to lexical pitch accent. Previous studies have mostly focused on pitch height/direction contrasts; however, languages use a variety of pitch features to signal meaning, including differences in pitch timing. In this study, we investigate infants'…

Word order is a core mechanism for conveying syntactic structure, yet interrogatives usually disrupt canonical word orders. For example, in English, polar interrogatives typically invert the subject and auxiliary verb and insert an utterance-initial "do" if no auxiliary is present. These word order patterns result from differences in the…

Research has indicated differences in prosodic expression for infants-at-risk-of-autism spectrum disorders (ASD), and it has been proposed that caregiver speech to these infants may also be moderated prosodically. In typical development, the pitch range of maternal infant-directed speech (IDS) narrows and utterance intensity decreases with infant…

Many studies have examined language acquisition under morphosyntactic or semantic inconsistency, but few have considered "word-form" inconsistency. Many young learners encounter word-form inconsistency due to accent variation in their communities. The current study asked how preschoolers recognize accent-variants of newly learned words.…