Can someone explain how rolling on/off tone changes sound of a note. How can a note change?

Chester P Squier

Friend of Leo's
Jan 16, 2021
Covington, LA
Yes A4 is 440 Hz and the A below it is 220 Hz. 330 Hz is an E or the 5th of A and is the dominant note that resolves to A. E is also one of the stronger harmonics and overtones of A. Actually E is 329.6 not 330 in a well tempered scale, but close enough. The well tempered scale is another interesting concept, but I don't wanna open that can of worms and hijack the thread.
Oh, I could get us off on a tangent about why D minor is the saddest of all keys.

Ok, it's because D major is the most resonant of all keys. And a harmonic of the root D is F#, which conflicts with the F natural.

Just one of my hare-brained theories.