Infant-directed speech : social and linguistic pathways in tonal and non-tonal languages

Social interaction is integral to language acquisition (Kitamura & Burnham, 2003; Snow, 1989). A key attribute of early social interaction is the caregivers' use of infant-directed (ID) speech with its greater affective salience, higher fundamental frequency (F0; pitch), wider pitch range (Kitamura & Burnham, 2003; Kitamura et al., 2002), and larger vowel space than adultdirected (AD) speech (Burnham, Kitamura & Vollrner-Conna, 2002; Kuhl et al., 1997). Evidence shows the emotion in its exaggerated prosody provides simultaneous attentional, and social-affective benefits (Kitamura et al., 2002; Snow, 1989), as well as assists infants in many of the challenges of early speech perception, e.g. to segment the speech stream (Theissen, Hill & Saffran, 2005), find stressed words in sentences (Fernald & Mazzie, 1991), discriminate multisyllabic words (Karzon, 1985), and parse clauses (Kemler Nelson et al., 1989). Overall, ID speech is ideal as a didactic tool due to its slowed speech rate, its simpler syntax and exaggerated prosodic and affective features. In this chapter, studies that include ID speech in tonal and non-tonal languages are reviewed to elucidate the universal and language-specific components as they relate to social, cultural and linguistic imperatives.