IntroductionThroughout the last Century the neogrammarian Regularity Principle (OsthoffBrugmann 1878(OsthoffBrugmann -1910, a product of early Twentieth-century, comparative reconstruction, and the lexical diffusion model (Wang 1969(Wang , 1979, which developed in reaction to neogrammarians' inability to deal effectively with irregularity, have had a strong impact on how sound change has been perceived and investigated in non-formalist accounts. However, (comparatively) recent research in sociolinguistics 1 and laboratory phonetics, which have uncovered the variability of language and the dynamics of human interaction, have drastically modified diachronic investigations. As a result, the neogrammarian and lexical diffusionist interpretations of sound change can be considered post-hoc labels of historical events that focus primarily on the initial stage and the final product of language change. This paper explores the cognitive, äs well äs the phonetic and sociological aspects of language use in order to approach a coherent Interpretation of the regularities, äs well äs the irregularities, of sound change through time. That is, ' [t]he key concept here is that of the course of evolution, which must be described not by correspondence rules which bridge the chasm of history between two (or among more) states, but by an account which traces the linguistic terrain covered by the bridge' (Cravens 1988: 80, his emphasis). The present study charts the linguistic terrain of sound change by focusing on the role of the individual and his/her interactions in the language Community within a cognitive, usage-based framework based on Langacker (1987,1988,2000) and Bybee (2000 a, b, 2001). In this model emergent language structures are the result of language users' ability to categorize and organize the variability of language (due to linguistic and sociolinguistic contexts and speech acoustics) during actual usage, and the propagation and entrenchment of these categorization routines in the speech Community.Once language use, Variation, and perception at the level of the individual äs well äs the Community become the focus of diachronic investigation, analyses of completed, regulär sound changes, which were once the prime interest of neogrammarians, cannot Departures from formalistic frameworks and research in sociolinguistics have been responsible for incorporating the Speaker into diachronic investigations. Evidence of this trend is found in and Joseph and Wallace (1992). More recently, Croft (2000) and Milroy (2003) insist that a sound theory of language change must recognize the role of individuals äs the force behind language change, rather than referring to language äs an abstract System that changes.Brought to you by | Purdue University Libraries Authenticated Download Date | 5/29/15 7:26 AM