As far as colors go, I've seen others assigned to the notes.
Is any one color "correct" for a particular note, or is this an individual choice? What I want to see is a translation of audio frequencies to visual frequencies. If found this low resolution map which looks interesting, but I don't want to use black and grey as colors. Middle C is 261.626 hertz and
The wavelength of each band of color in the visible spectrum (measured in nanometers, nm) can be halved repeatedly until the rate of its vibration falls within the octaves of the audible spectrum (measured in Hertz, Hz), giving a table of musical notes that correspond to each color (see Figure 2).
Eric L. Wagner of wagneric.com has an interesting analysis with a chart:
Light is a part of the electromagnetic spectrum, higher in frequency than radio waves, but below X-rays. Wavelengths we can see are between approximately 380nm and 780nm. Curiously, the spectrum of visible light, between ultraviolet and infrared, is almost exactly an octave, with the visible edge of ultraviolet having double the frequency (and half the wavelength) of the visible edge of infrared. ...
Corresponding light-spectrum harmonics were computed from equal temperament musical pitches, using a reference of A440 and a half-step frequency ratio of 21/12. Given the speed of light, C = 299792458 meters/second, and λ=C/F, wavelengths were computed for each frequency. The 780.75nm "F" falls outside of the 380-780nm range but I added it for interest. Note that exactly 12 pitches fit within the range. The light spectrum "C" is 41 octaves above middle-C
F -- 349.228231 Hz ~ 383.980501 THz ~ 780.749171 nm
F# -- 369.994423 Hz ~ 406.813170 THz ~ 736.929087 nm
G -- 391.995436 Hz ~ 431.003540 THz ~ 695.568436 nm
G# -- 415.304698 Hz ~ 456.632344 THz ~ 656.529179 nm
A -- 440.000000 Hz ~ 483.785116 THz ~ 619.681028 nm
Bflat -- 466.163762 Hz ~ 512.552476 THz ~ 584.901004 nm
B -- 493.883301 Hz ~ 543.030432 THz ~ 552.073033 nm
C -- 523.251131 Hz ~ 575.320702 THz ~ 521.087555 nm
C# -- 554.365262 Hz ~ 609.531052 THz ~ 491.841158 nm
D -- 587.329536 Hz ~ 645.775654 THz ~ 464.236235 nm
Eflat -- 622.253967 Hz ~ 684.175473 THz ~ 438.180657 nm
E -- 659.255114 Hz ~ 724.858663 THz ~ 413.587466 nm
F -- 698.456463 Hz ~ 767.961002 THz ~ 390.374586 nm
My eye has trouble telling the difference between the different reds, greens and purples in this chart above. Anyway, when I take the visible spectrum and use a ruler in a graphics program and put Middle C exactly in the middle, I get this color, a mix of sun and green grass.
The Real Middle "C"