In folk music, before 1939, and for some time afterward, I suppose that A=432 was more common than any other tuning. Now it's A=440, of course. With few exceptions. My own folk music efforts, for example.
In a new site I've started putting together, you can hear some of these earlier tunings. The site is Best Blues Music Videos. Some of the performances go way back.
For example a performance of Hesitating Blues by Jelly Roll Morton, sounds like the piano is flat even to A=432.
On the other hand, the same tune by Fiddlin Arthur Smith, (not posted), from about the same time, has the fiddle sharp even by contemporary standards.
I don't really know what to make of this. It occurred to me that old recordings may have, in some cases, had the pitch raised in the studio during the remastering. But, how could I find that out for sure?
Milk Cow Blues
5 months ago