There has been much recent interest in to what extent an individual’s phonetics and phonology changes over time, from two perspectives. In short-term= laboratory settings, aspects of one’s speech shift in response to the speech of others; such ‘convergence’ effects are mediated by social and linguistic factors, and are well-attested (Goldinger, 1997; Pardo, 2006; Nielsen, 2008; Babel, 2009). It has been hypothesized that an accumulation of such shifts over time is an important source of accent change in individuals and sound change in communities (Pardo, 2006; Delvaux & Soquet, 2007). However, studies where phonetic or phonological variables are remeasured for individuals at times years apart have found huge variability: there is often no evidence for any change for a majority of individuals, while a minority change significantly (Harrington, 2006; Evans & Iverson, 2007; Sankoff & Blondeau, 2007; Siegel, 2010). What is the link between the different patterns seen in short-term convergence and long-term dynamics?
We address this question by investigating ‘medium term’ phonetic and phonological variation in a British reality television show where speakers live in an isolated house for three months, subject to constant recording. The house is a socially and linguistically closed system, making it possible to trace the dynamics of phonetic and phonological variables in contestants’ speech, and to test hypotheses about their sources. We consider three variables — two phonetic (VOT, vowel formants) and one phonological (t/d deletion) — in 8 hours of speech from 12 speakers. We analyze each variable’s dynamics over the course of the season after controlling for linguistic factors. Different speakers show extremely different dynamics for particular variables: some do not change at all over time, some show significant short-term fluctuations without long-term trends, and some show long-term trends. The most common pattern is for a speaker’s use of a variable to fluctuate between recording sessions on different days, in part due to shifts in the topic of conversation. There are also some possible effects of social interaction on observed dynamics. Our findings suggest that short-term shifts in individuals’ speech (days) are common, but only accumulate into longer-term change for some speakers.