Published online by Cambridge University Press: 18 December 2008
Although the rates of changes in language are customarily described in relative terms, this paper presents a method of quantifying the rate of a given change during a specific time period. Utilizing the results of recent studies of sound change in progress, the Rate of Change Index is applied to the data for the purpose of indicating precisely the speed of these changes. Also measured in this manner are the rates of change of a variable in different phonetic contexts and among different social classes. The comparisons made here lend support to two important theories: that linguistic change follows an S-curve and that change proceeds more rapidly in urban than in rural areas. The Index contributes, then, to an inductive model of sociolinguistic change. It is also suggested that the Index can be applied to syntactic and lexical changes as well. (Linguistic change, Sociolinguistics, Phonology.)