This is very common in rock music. Out of tune=dissonance, Squeak = pinch harmonics.
Some classical piano composers had instructions to do things like put objects between piano strings for effect.
As to the missed note, same composer as linked has a piece that contains no notes whatsoever. 4 33
^^ Cage’s concerto or whatever is just about the stupidest thing I’ve never heard. Guess I simply don’t appreciate good music.
“John Cage….prodded us to reevaluate how we define not only music but the entire experience of encountering art.” Oh pullllease, get over your pretentious self.
@smudges 4 33? I had to read up on it a little after posting this. You’re supposed to sit in silence and carefully listen to the ambient environment. Appreciation of it was apparently the point. I would not call it stupid, just off the wall artsy. Putting it in “music” forces an entire audience to participate.
Not sure what the musical note for a squeak would be, though missed notes can readily be put in. The harder version would be to musically right the slide of vocals. Bob Dylan did this spectacularly.