Wow, holy crap guys, wasn’t expecting that response!
I figured I’d answer all of you in one reply, less clutter that way!

Well now I’m fascinated. Lemme ask you this: can you perceive shades of that gold if the Bb is 20 cents off? How do you perceive slow, continuous sweeps of tone? Say from A to C? Man, brains are weird and awesome.
It’s like a fader switch.
Moving from A to C slowly and smoothly I’d see it go from orange, to amber, to gold, to yellow, and to green, which is C.
So if it is quiet, are there no colors? Where do the colors show up in your vision? What happens if you hear a chord or someone talking? Do notes an octave up or down have the same color? Do you have 12 distinct colors for 12 notes?
Generally speaking, the colors get more definite the louder the music is, and they tend to wash out the quieter the music is.
There’s also two types of synesthetes when it comes to visual forms of synesthesia: projectors and associators.
Associative synesthesia is like when you see the color in your mind, but not your vision.
Projective synesthesia is like you see the color in your vision like it’s on a screen in your visual field.
For me, they look different depending on the timbre of the instrument and the performance, but notes look like small, vibrating musical dots, not unlike what you’d see in sheet music.
I do have 12 distinct colors for the 12 notes, and generally, the higher in pitch, the brighter the hue of the color is, and the lower the pitch, the darker it tends to be.
As far as the colors, for the natural notes, A-B-C-D-E-F-G, they look like this:
- A = orange.
- B = yellow.
- C = green.
- D = blue.
- E = indigo/dark/navy blue.
- F = purple.
- G = red.
And for the accidentals, they’re kinda in between, and are:
- A#/Bb = amber or gold.
- C#/Db = cyan.
- D#/Eb = blue violet.
- F#/Gb = magenta.
- G#/Ab = vermilion.
As you can see, between D up to E is like a wash of blue-ish, so sometimes I have a hard time figuring out D, D#/Eb, and E. I usually tend to trust that pure blue is D, pure indigo is E, and the dark in-between color which I’m calling blue-violet is D#/Eb.
Chords simply just look like stacked notes to me, so it’s not like they blend together. Makes inversions really easy to understand.
Keys are the real weird one, they show up kinda like a color filter and more of a general vibe and feeling.
For example, my favorite piece from Dark Souls III is the Farron Abyss Watchers Theme.
To me, it shows up as a rich, dark plum color. The purple leads my brain into thinking our root note is F, and the darker color gives me the feeling this is in a minor key.
As far as voices, those are the most distinct and varied amongst any musical instrument, and a lot of times people have a unique voice, so they each have a unique color, and sometimes that color is one I can’t even name because it’s in-between an in-between color, lol. For reference, Bruce Dickinson is a powerful blue, Pavarotti is the closest you can get to a gold voice without being gold. I dunno, it’s like a rich in-between amber and gold sorta color. Sopranos tend to be very bright, and Simone Simons of Epica is a very bright almost star-like yellow.
Voices are the hardest for me because they’re so unique and dynamic. Even the colors I used are approximations because the beauty of singing is being so good to be able to sing dead on the note, but choosing to go ever so sharp or flat of the note for reasons of overtones.
If it’s more definite, and it’s singing, that’s how I can tell it’s auto-tuned, because the natural human voice is more expressive and dynamic.
And what about the overtones? Do you see shades of the other colors in it?
Overtones add up to different timbres to me, which skew what I see, giving instruments their own tone-color.
Guitars are a rich blue, violins are a bright red, cellos, a dark more blood red, trumpets a bright gold, flutes, almost a completely washed green, pianos a rich green.
Like keys, it’s more of a filter and general vibe, not really definite like notes are, if any of this is making sense, lol.
But generally, most music is like a wash of dynamically changing color, and some genres excite my synesthesia more.
As you can imagine, crowded shopping centers, loud, incongruous noises, white noise (more like gray noise for me), and binaural beats are just… ugly to me.
Music though, is very awesome, and THC tends to amplify things.
Considering I’m ADHD and autistic too, I do take stimulants to manage my ADHD, and the medication attenuates my synesthesia somewhat.
So, yeah. Hope this gives you all an insight into what I experience.