I was wondering about how strong are the region-wide or country-wide mass-media institutions (be them newspapers or TV channels) as deterrent of language or dialects differentiation.
For example, a nation-wide TV channel based in some city (usually the capital) would record and broadcast its shows in the dialect of that city, a likely different one than those of the most distant regions of the same country.
And we also have several channels spanning many countries, but I am not sure how influential are these ones on the population.
Are there any serious evidence that the usual and systematic differentiation of the dialects is being deterred by the existence and importance of these institutions?
P.S. I've found three questions related to this one, but they cover somewhat different topics:
Impact of widespread literacy and global communication on language evolution: this one focuses on literacy and global communication as a whole, not only to mass-media.
How powerful is literacy to slow down language change?: this focuses only on literacy.
Is there any evidence that modern telecommunication slows dialect differentiation?: this focuses on modern telecommunication, very related to this question, but it didn't get any answers.