I suspect the advent of recorded sound has had a huge effect on slowing down the drift or oral languages as well. Just think, in the 1930's people wouldn't rea

I suspect the advent of recorded sound has had a huge effect on slowing down the drift or oral languages as well. Just think, in the 1930's people wouldn't really know what people sounded like in the 1850's, unless they had a very long-lived relative. Here in the 2010's, we have those sound movies from the 1930's to refer to, even though most of those actors and actresses are long gone now. (And they're still perfectly intelligible, even if the slang is sometimes odd to our ears). And hopefully in the 2090's, they'll still have those 1930's movies around...