Web Site Shows British Accent Development
Recordings of voices from the 1950s, the 1980s and 1990s on a new Web site show that older pronunciations like "toon" for town and "coo" for cow are fading, replaced with more standard forms, officials say.
[...] The use of "toon" — which once spread as far south as Yorkshire — does survive in some of the broader Newcastle accents and in some Scottish pronunciations, he said.
Among other major changes has been the "virtual disappearance" of the Northumbrian burr, the way some residents of northeast England have of pronouncing an initial "r" sound at back of the throat, as in French, rather than the front.
The British Library "Collect Britain" website is here.

