The private life of stops: VOT in a real-time corpus of spontaneous Glaswegian

While voice onset time (VOT) is known to be sensitive to a range of phonetic and linguistic factors, much less is known about VOT in spontaneous speech, since most studies consider stops in single words, in sentences, and/or in read speech. Scottish English is typically said to show less aspirated voiceless stops than other varieties of English, but there is also variation, ranging from unaspirated stops in vernacular speakers to more aspirated stops in Scottish Standard English; change in the vernacular has also been suggested. This paper presents results from a study which used a fast, semi-automated procedure for analyzing positive VOT, and applied it to stressed syllable-initial stops from a real- and apparent-time corpus of naturally-occurring spontaneous Glaswegian vernacular speech. We confirm significant effects on VOT for place of articulation and local speaking rate, and trends for vowel height and lexical frequency. With respect to time, our results are not consistent with previous work reporting generally shorter VOT in elderly speakers, since our results from models which control for local speech rate show lengthening over real-time in the elderly speakers in our sample. Overall, our findings suggest that VOT in both voiceless and voiced stops is lengthening over the course of the twentieth century in this variety of Scottish English. They also support observations from other studies, both from Scotland and beyond, indicating that gradient shifts along the VOT continuum reflect subtle sociolinguistic control.