Table_1.docx

Tonal information is essential to early word learning in tone languages. Although numerous studies have investigated the intonational and segmental properties of infant-directed speech (IDS), only a few studies have explored the properties of lexical tones in IDS. These studies mostly focused on the first year of life; thus little is known about how lexical tones in IDS change as children’s vocabulary acquisition accelerates in the second year (Goldfield and Reznick, 1990; Bloom, 2001). The present study examines whether Mandarin Chinese mothers hyperarticulate lexical tones in IDS addressing 18- and 24-month-old children—at which age children are learning words at a rapid speed—vs. adult-directed speech (ADS). Thirty-nine Mandarin Chinese–speaking mothers were tested in a semi-spontaneous picture-book-reading task, in which they told the same story to their child (IDS condition) and to an adult (ADS condition). Results for the F0 measurements (minimum F0, maximum F0, and F0 range) of tone in the speech data revealed a continuum of differences among IDS addressing 18-month-olds, IDS addressing 24-month-olds, and ADS. Lexical tones in IDS addressing 18-month-old children had a higher minimum F0, higher maximum F0, and larger pitch range than lexical tones in ADS. Lexical tones in IDS addressing 24-month-old children showed more similarity to ADS tones with respect to pitch height: there were no differences in minimum F0 and maximum F0 between ADS and IDS. However, F0 range was still larger. These results suggest that lexical tones are generally hyperarticulated in Mandarin Chinese IDS addressing 18- and 24- month-old children despite the change in pitch level over time. Mandarin Chinese mothers hyperarticulate lexical tones in IDS when talking to toddlers and potentially facilitate tone acquisition and word learning.

在声调语言中，声调信息对早期词汇学习至关重要。尽管已有大量研究探讨了婴儿导向言语（infant-directed speech, IDS）的语调与音段特征，但仅有少数研究关注了IDS中词汇声调的属性。现有此类研究大多聚焦于生命的第一年，因此对于儿童词汇习得速度加快的第二年，IDS内词汇声调的变化规律仍鲜为人知（Goldfield与Reznick, 1990; Bloom, 2001）。
本研究旨在探究汉语普通话（Mandarin Chinese）母亲在面对18、24个月龄儿童的IDS中，是否会对词汇声调进行超清晰发音，并与成人导向言语（adult-directed speech, ADS）进行对比——此年龄段儿童正处于词汇快速习得阶段。
本研究招募39名汉语普通话母语母亲，采用半自发图画书阅读任务开展测试：母亲需分别向自己的孩子（IDS组）与一名成人（ADS组）讲述同一故事。
对语音数据中声调的基频（F0）测量结果（包含最小基频、最大基频与基频范围）显示，针对18月龄儿童的IDS、针对24月龄儿童的IDS与ADS三者间存在梯度差异。相较于ADS中的词汇声调，针对18月龄儿童的IDS内的词汇声调具有更高的最小基频、更大的最大基频与更宽的音高范围。针对24月龄儿童的IDS内的词汇声调，其音高高度与ADS声调更为接近：ADS与IDS的最小基频、最大基频均无显著差异，但基频范围仍更宽。
上述结果表明，尽管音高水平随儿童年龄增长发生变化，但汉语普通话母亲在对18、24个月龄儿童使用的IDS中，通常会对词汇声调进行超清晰发音。汉语普通话母亲在与学步儿童交流时，会在IDS中强化词汇声调的发音，这可能有助于儿童的声调习得与词汇学习。