[gardano]

Take a gander at an actual 17th century composer playing with that idea in a most audacious way [0]. The section of the piece I'm referring to begins around 3:26.

The idea seems to be, keys that are foreign to the piece should sound dissonant.

[0]: https://www.youtube.com/watch?v=BbrrMtWICs4

[pYQAJ6Zm]

I am not a musician and, after listening to the piece, I was left with a question. To me, that part does sound playfully dissonant, yet it’s enjoyable. But I wonder, is this dissonance just a product of its key being foreign to the piece, as you say, or is there any chord in use that would be considered dissonant by music theory?

[gardano]

It's got more to do with the tuning system.

Think of it as '6 degrees of separation'. The further away I am away from the starting point, the more alien the tuning would be, and therefore the more startling the sound.

During this period in music, the ideal was to make the 'home base' key to be as perfectly in tune as possible (making adjustments of course).

Michelangelo Rossi is playing with this, and is pushing the boundaries of those assumptions. William Byrd did much the same in England at pretty much the same time.

It makes me wonder if the hyper-specialised quarter-tone composers of our day might have had a better time of it if we had never adopted equal temperament as the standard…

[tprice7]

That's an interesting idea and piece, thanks for sharing.

[leephillips]

That is wild. Thanks for sharing.