title: Utterances in infant-directed speech are shorter, not slower.
abstract: It has become a truism in the literature on infant-directed speech (IDS) that IDS is pronounced more slowly than adult-directed speech (ADS). Using recordings of 22 Japanese mothers speaking to their infant and to an adult, we show that although IDS has an overall lower mean speech rate than ADS, this is not the result of an across-the-board slowing in which every vowel is expanded equally. Instead, the speech rate difference is entirely due to the effects of phrase-final lengthening, which disproportionally affects IDS because of its shorter utterances. These results demonstrate that taking utterance-internal prosodic characteristics into account is crucial to studies of speech rate.
authors: Laboratory for Language Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan; Konan University, Department of English Literature and Language, 8-9-1 Okamoto, Higashi Nada-ku, Kobe 658-0072, Japan. Electronic address: amartin@center.konan-u.ac.jp.
authors: Andrew
authors: A
authors: Martin
authors: Hitotsubashi University, Graduate School of Social Sciences, 2-1 Naka, Kunitachi-shi, Tokyo 186-8601, Japan.
authors: Yosuke
authors: Y
authors: Igarashi
authors: Waseda University, School of Human Sciences, 2-579-15 Mikajima, Tokorozawa-shi, Saitama 359-1192, Japan.
authors: Nobuyuki
authors: N
authors: Jincho
authors: Laboratory for Language Development, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan; Duke University, Department of Psychology and Neuroscience, Box 90086, 417 Chapel Drive, Duke University, Durham, NC 27708-0086, United States.
authors: Reiko
authors: R
authors: Mazuka
mesh_terms: D000328:Adult; D044466:Asian People; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D009034:Mother-Child Relations; D013060:Speech; D013068:Speech Production Measurement; D013997:Time Factors
keywords: Final lengthening; Infant-directed speech; Speech rate