Iwamoto Kyoji, Kikuchi Hideaki, Mazuka Reiko
Center for Brain Science, RIKEN, Wako, Saitama 351-0106, Japan.
Faculty of Human Sciences, Waseda University, Tokorozawa, Saitama 359-1192, Japan.
J Exp Child Psychol. 2022 Aug;220:105411. doi: 10.1016/j.jecp.2022.105411. Epub 2022 Mar 26.
Development of speech rate is often reported as children exhibiting reduced speech rates until they reach adolescence. Previous studies have investigated the developmental process of speech rate using global measures (syllables per second, syllables per minute, or words per minute) and revealed that development continues up to around 13 years of age in several languages. However, the global measures fail to capture language-specific characteristics of phonological/prosodic structure within a word. The current study attempted to examine the developmental process of speech rate and language-specific rhythm in an elicited production task. We recorded the speech of Japanese-speaking monolingual participants (18 participants each in child [5-, 7-, 9-, 11-, and 13-year-old] and adult groups), who pronounced three types of target words: two-mora, two-syllable words (CV.CV); three-mora, two-syllable words (CVV.CV); and three-mora, three-syllable words (CV.CV.CV), where C is consonant and V is vowel. We analyzed total word duration and differences in two pairs of word types: a pair of three-mora words (to show the effect of syllables) and a pair of two-syllable words (to show the effect of moras). The results revealed that Japanese-speaking children have acquired adult-like word duration before 11 years of age, whereas the development of rhythmical timing control continues until approximately 13 years of age. The results also suggest that the effect of syllables for Japanese-speaking children aged 9 years or under was stronger than that of moras, whereas the effect of moras was stronger after 9 years of age, indicating that the default unit for children in speech rhythm may be the syllable even when the language is mora-based.
人们常说，儿童的语速发展呈现出在青春期之前语速逐渐降低的趋势。以往的研究使用全局测量方法（每秒音节数、每分钟音节数或每分钟单词数）来研究语速的发展过程，并发现多种语言的语速发展一直持续到13岁左右。然而，这些全局测量方法未能捕捉到单词内音系/韵律结构的语言特定特征。本研究试图在一个诱发产出任务中考察语速和语言特定节奏的发展过程。我们记录了说日语的单语参与者（儿童组[5岁、7岁、9岁、11岁和13岁]和成人组各18名参与者）的语音，他们朗读三种类型的目标单词：双拍、双音节单词（CV.CV）；三拍、双音节单词（CVV.CV）；以及三拍、三音节单词（CV.CV.CV），其中C为辅音，V为元音。我们分析了总单词时长以及两对单词类型之间的差异：一对三拍单词（以显示音节的影响）和一对双音节单词（以显示拍的影响）。结果显示，说日语的儿童在11岁之前就已经获得了类似成人的单词时长，而节奏定时控制的发展一直持续到大约13岁。结果还表明，9岁及以下说日语的儿童，音节的影响比拍的影响更强，而9岁之后拍的影响更强，这表明即使语言是以拍为基础的，儿童在语音节奏中的默认单位可能仍是音节。
