Listeners tend to perceive longer vowels as word-final and include the aspiration of a syllable-onset consonant in metalinguistically judging the duration of the following vowel. It may be hypothesized that longer aspiration is interpreted as extra vowel duration and hence, a word-finality cue. Alternatively, if aspiration is perceived as part of the onset, longer aspiration should be interpreted as word-initial, consistent with previous findings on consonant lengthening [White, Mattys, Stefansdottir, and Jones (2015). J. Acoust. Soc. Am. 138(2), 1214–1220]. An artificial language learning experiment with Taiwanese Southern Min listeners showed that lengthening aspiration in word-initial but not word-final syllables improved speech segmentation, supporting the second but not the first hypothesis.