Systematic F1 increase in Korean aegyo speech may signal childlike qualities.

Korean aegyo is a socially recognized childlike speaking style used predominantly in romantic interactions among adults. This study examined vowel space modification in aegyo by analyzing formant frequencies from twelve Seoul Korean speakers who produced identical scripts in aegyo and non-aegyo styles. Results show that aegyo speech features a significant increase in F1 values across vowels and selective fronting of front vowels, leading to some expansion of the vowel space but mainly shifting to higher F1. These findings motivate the hypothesis that adult speakers construct a childlike vocal quality by increasing F1, possibly through a combination of different factors like global vowel lowering and partial fronting.