Appendix 3. Cohen’s d for F1 across Speech Conditions

Vowel	Measure	d (Read vs. ConvNK)	d (Read vs. ConvSK)
[i]	F1	–0.7	–0.88
[e]	F1	0.56	0.4
[æ]	F1	0.57	0.57
[ʌ]	F1	0.51	0.54
[o]	F1	–0.23	–0.1
[ɯ]	F1	–0.42	–0.45
[u]	F1	–0.58	–0.65
[a]	F1	0.533	0.44

Positive d-values indicate an increase in F1 or F2 (lowering or fronting), while negative values indicate a decrease (raising or backing). Effect sizes of |d| ≥ 0.20 are considered small, |d| ≥ 0.50 moderate, and |d| ≥ 0.80 large. NK, North Korean standard; SK, South Korean standard. Data from Cohen (1988).