Internal and external motivation in phonetic change: Dialect levelling outcomes for an English vowel shift

Abstract

This article is a contribution to the debate about the primacy of internal versus external factors in language change (Farrar and Jones 2002; Thomason and Kaufman 1988). Taking Labov's Principles of Vowel Shifting (Labov 1994) as representing internal factors, we examine a vowel shift in Ashford, south‐east of London. F1 and F2 measurements of the short vowels suggest a classic chain shift, largely following Labov's Principles II and III (though Labov's assumption that London short front vowels are rising is shown to be wrong). However, corresponding data from Reading, west of London, evidence no signs of a chain shift. The two datasets show identical targets for the changes in each town. Thus, there has been convergence between the two short vowel systems – from different starting points. We argue that a dialect contact model is more explanatory than internal factors in this case of regional dialect levelling in the south‐east of England.