Hey Lieven!
I knew someone once whom, when another friend was showing his whistling key ring, announced "That's an Eb you have to whistle!"
!?
The closest I've come to that is with the piano. Now I don't know the guitar THAT well (I'd have to work out what the note is above the 5th - 7th fret - and many is the time I've sat down with a guitar neck chart or started writing my own to learn it (my laziness!)) but the piano I know less well - I know most major, minor, flat, sharp ,and 7th chords (or can quickly work out) but my knowledge of songs is a pattern I learn of where my fingers go to at a certain time rather than "I'm, playing an Eb 7th," or whatever.
However, I got to the point with piano that things "just happened;" a song or piece of music, usually by an established artist, would come out of nowhere, my fingers would find the chords and the runs without thinking about/realising what I was doing!
But no, I don't think in Eb, A 9th or whatever. Give me one true note tho' and a blank stave and as long as I have that one note for continual reference I could write out a simple tune that's in my head.
The closest I could say to coming to the point of being able to think it is with audio equipment; I can work out the input, bus routing and alternatives for an input in my head away from the studio (hearing an audio source and correcting the EQ is however one part I can do entirely in my head with 95% accuracy.) I used to ask my degree students to tell me how many different ways there were of aquiring one signal (mic or guitar or etc) the most they came up with was 40 - 42! I would have to sit down and think of them all to remember how many.
I believe the secret of perfect pitch is to associate each note with a colour, but know no more than that.
It is my belief that knowledge of music theory is not necessary to be a GREAT musician, knowledge of your instrument IS!
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