When Did Americans Lose Their British Accents?

There are many, many evolving regional British and American accents, so the terms “British accent” and “American accent” are gross oversimplifications. What a lot of Americans think of as the typical "British accent” is what's called standardized Received Pronunciation (RP), also known as Public School English or BBC English. What most people think of as an "American accent," or most Americans think of as "no accent," is the General American (GenAm) accent, sometimes called a "newscaster accent" or "Network English." Because this is a blog post and not a book, we'll focus on these two general sounds for now and leave the regional accents for another time.
English colonists established their first permanent settlement in the New World at Jamestown, Virginia, in 1607, sounding very much like their countrymen back home. By the time we had recordings of both Americans and Brits some three centuries later (the first audio recording of a human voice was made in 1860), the sounds of English as spoken in the Old World and New World were very different. We're looking at a silent gap of some 300 years, so we can't say exactly when Americans first started to sound noticeably different from the British.
As for the "why," though, one big factor in the divergence of the accents is rhotacism. The General American accent is rhotic and speakers pronounce the r in words such as hard. The BBC-type British accent is non-rhotic, and speakers don't pronounce the r, leaving hard sounding more like hahd. Before and during the American Revolution, the English, both in England and in the colonies, mostly spoke with a rhotic accent. We don't know much more about said accent, though. Various claims about the accents of the Appalachian Mountains, the Outer Banks, the Tidewater region and Virginia's Tangier Island sounding like an uncorrupted Elizabethan-era English accent have been busted as myths by linguists.

Read the full text here: http://mentalfloss.com/article/29761/when-did-americans-lose-their-british-accents#ixzz2J0ZLUztc
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