Regional variation and change of Tai dam single initials

This paper presents a study on regional variation of Tai Dam initial single consonants in three locations, Thailand, Laos, and Vietnam. Tai Dam or Black Tai language was selected as a case study because it is spoken by a significant ethnic group in the three ASEAN (Association of Southeast Asian Nations) countries. The research sites include locations which have never or for over a decade been studied so that a diachronic comparison can be examined. The framework used in this study is Variation Theory in which Tai Dam single initials are used as dependent variables, with the locations of Tai Dam speakers serving as independent variables. Based on the variation and change of the Tai Dam single initials, they are classified into three groups. The first group consists of thirteen single initials which remain intact. The second group includes five initials which internally change from Old Tai Dam and show no regional variation. The last group has nineteen single initials which change from Old Tai Dam and are varied according to locations in Thailand, Laos, and Vietnam. The regional variation is caused basically by language contact which is an important external factor. Most Tai Dam people in the three countries are bilingual so the majority languages have definitely influenced.