/aʊ/ monophthongization in Pittsburgh

One of the more unusual characteristics of Pittsburgh speech is the monophthongization of [aʊ] to [a:]. Unlike the case of /aɪ/ , monophthongization of /aʊ/ is rare in American English and has not been reported outside of Western Pennsylvania. Locally, social awareness of this feature is high, and it is commonly exemplified by spelling downtown as “dahntahn”. Monophthongization occurs in a variety of phonological contexts including following nasals (e.g., downtown), liquids (e.g., fowl, hour), and obstruents (e.g., house, out, cloudy). It is not found, however, word finally (e.g., how, now). Monophthongization appears to be especially characteristic of white working class speakers. Its origins are not well documented, but it seems to have arisen in the late nineteenth or early twentieth centuries during a period of rapid industrial growth for the city. At that time Pittsburgh saw a great influx of immigrants speaking other dialects as well as other languages, and monophthongal /aʊ/ is likely a product of that dialect contact.