A real-time study of plosives in Glaswegian using an automatic measurement algorithm: Change or age-grading?

This paper presents a collaborative study of variation and potential change in the voicing contrast in Scottish English plosives, analyzed in recordings from twelve vernacular female speakers of different generations made in the 1970s and the 2000s in Glasgow. We adapted an existing automatic measurement algorithm for predicting Voice Onset Time (VOT) originally developed for voiceless stops, for the analysis of voiced and voiceless plosives in casual sociolinguistic speech recordings of different kinds. Our semi-automatic method, which involved quick manual coding of automatically-generated positive VOT predictions, resulted in correct or close to correct measures for two-thirds of our data, and allowed us to process a very large number of tokens very quickly, especially for voiceless stops. The VOT results themselves indicate that the voicing contrast is being maintained, but suggest that a change in the phonetic realization of the stops may have been in progress since the middle of the 20th century, specifically a lengthening of aspiration for /p/ and /t/, and a trend to a longer release phase in their voiced counterparts.