I've been meaning to get this for a long time, and finally did.
Here we have 10 pieces (112 minutes) for piano in untempered tuning. In theory, chords sound much more in tune this way, but only in one key, so the music has to stay away from modulations.
I'm enthusiastic about this kind of thing, but I wasn't sure what to expect with Terry Riley at the keyboard (it could have been all one chord

). Turns out it's very good.
I would think that with electronic keyboards it should be possible to develop programs that would allow one to play in untempered tuning in all keys, even as the music modulates. Is anybody working on that?
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I don't do it for the money, babe. I do it to entertain people.-- Susan Boyle