We investigate whether child-directed speech (CDS) contains a higher proportion of canonical pronunciations compared to adult-directed speech (ADS), focusing on Korean noun stem-final obstruent variation. In a word-teaching task, we observed that mothers use a higher rate of canonical pronunciation when addressing infants than when addressing adults. In a follow-up experiment, adults exhibited a higher rate of canonical pronunciation for high- than low-frequency words. Additional analyses conducted with only the high-frequency monosyllabic words from the two experiments found no evidence for simplified phonology in CDS when lexical frequency was controlled for. Our findings suggest that the higher rate of canonical forms in CDS, with respect to Korean morphophonological rules, is mediated by the frequency of word usage. Thus, the didactic function of CDS phonology appears to be a byproduct of mothers using familiar words with children. These results highlight the importance of considering word usage in investigating the nature of CDS.

我们调查了与成人定向语音 (ADS) 相比，儿童定向语音 (CDS) 是否包含更高比例的规范发音，重点关注韩语名词词干词尾的晦涩变体。在一项单词教学任务中，我们观察到母亲在对婴儿说话时比对成人说话时使用规范发音的比例更高。在后续实验中，成年人对高频单词的规范发音高于低频单词。仅对两个实验中的高频单音节词进行的额外分析发现，当控制词汇频率时，CDS 中没有简化音系的证据。我们的研究结果表明，就韩语形态语音规则而言，CDS 中规范形式的较高比例是由单词使用频率调节的。因此，CDS 音韵学的教学功能似乎是母亲对孩子使用熟悉的单词的副产品。这些结果凸显了在调查 CDS 性质时考虑词语使用的重要性。