Individual differences in vowel compactness persist under intoxication across first and second languages

Alcohol intoxication facilitates inhibition of one’s first language (L1) ego, which may lead to reduced individual differences among second language (L2) speakers under intoxication. This study examined whether, compared to speaking while sober, speaking while intoxicated would reduce individual differences in the acoustic compactness of vowel categories in sequential bilinguals exemplifying diverse L1–L2 pairs (German–English, Korean–English). Vowel compactness in F₁ x F₂ space varied by language (German, Korean, English) and by vowel, and was generally lower in intoxicated compared to sober speech, both across languages and throughout a bilingual’s language repertoire. Crucially, however, there was still a wide range in compactness under intoxication; furthermore, individuals with more compact vowels while sober also produced more compact vowels while intoxicated, in both L1 and L2. Taken together, these findings show patterned variability of vowel compactness, suggesting that articulatory precision is an individual-difference dimension that persists across speaking conditions and throughout the repertoire.

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