American women are in the vanguard of speech innovation

You can start watching at 2:18-2:55 to understand what he's on about. 

At 7:03 he gives some surprising examples from social media of this phenomenon. 

But here's a sentence that really surprised me. This phonetic linguist says @7:46 "It may be that young American women are in the vanguard, as they often are in speech innovations."