I don’t know but in the days when we would get a ‘front of house mix’ in the PA foldback at our gigs back around 1980, I would always wear an Aussie made acubra hat so I could hear myself better. It provided the right amount of sound reflection into my ears. Maybe the same could be said for those days, mandolins and guitars can be hard to hear up on stage and in those times there probably wasn’t any foldback. Plus there was a lot of harmony singing going on. Horn players in jazz bands wouldn’t have had that problem.

The Stanley Brothers wore stockmen’s hats—with a smaller brim and a different crown than cowboy hats. I always preferred those. But why Bill Monroe chose cowboy hats I have no idea. I do think that they’d make doing an outdoor stage show in sunny weather easier and more comfortable.

Cowboy movies were very popular in the period when country music was emerging--the 1920s, '30s, and '40s. The image of the heroic cowboy was imbued with all sorts of positive implications. The image of the mountaineer/hillbilly, much less so.

I've read a bunch of discussions of this phenomenon. A good one can be found in this book: press.uchicago.edu/ucp/books/b...5068.html .

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The music genre used to be called Hillbilly music. At the time, that was not considered to be a pejorative description. Sometime in Fourties or Fifties the genre became Country and Western music, and a lot of the performers adopted western-style apparel.

I suspect that the name change was the work of some marketing folks associated with the music recording and publishing business. It would appear to be an early example of political correctness.

Or….

.... monkey see, monkey do??

To adequately address the topic [i.e. head-to-toe] ...  I was wearing these bay boys at a festival a couple of weeks back and a lady asked if the duct tape was a fashion statement.  Apparently my imagination was AWOL, so I gave the very pedestrian truth ... the original was uncomfortable on the high instep (?) of my left foot, so I cut the [no-name] clog and spread it into a "V" and used duct tape to keep things in place.   

I trust youse guys realize how fortunate you are .... IF I was an accomplished player, y'all would now be out buying/cutting/duct taping your left clog.  

when set best --they supposedly funnel the sound--

Who in the heck needs a hat when you could just use an ear trumpet??