Is there some "formulae" for mixing frequencies that perform similar effects? I recall reading something a few years ago (it was likely posted here) about discordant tones.
They are actually always occurring (if the notes as sufficiently dissonant) - so the calculations are nothing more than subtraction ie. 440 - 215 = 5hz
some combination tones are louder than others usually as there is less phase cancellations occurring.
Is there some "formulae" for mixing frequencies that perform similar effects? I recall reading something a few years ago (it was likely posted here) about discordant tones.
Try going to a piano, and playing two notes, black or white, that are immediately next to each other at the same time (a half-step interval).
Further listening: Modest Mussorgsky's The Hut of the Baba Yaga, or Miles Davis' Someday My Prince Will Come.
these are called "tartini beats"/"combination tones" etc: https://en.wikipedia.org/wiki/Combination_tone
They are actually always occurring (if the notes as sufficiently dissonant) - so the calculations are nothing more than subtraction ie. 440 - 215 = 5hz
some combination tones are louder than others usually as there is less phase cancellations occurring.
I think you got the principle right but used the wrong A for your example (you used A4, probably meant to use A3)?
440 and 215 would interact as 440 and 430 (an octave above the 215) so you'd get a difference of 10 Hz, not 5. (And the sums as well, of course.)