These Max/MSP patches take stereo sound and displays 6 blocks of colour corresponding to the fundamental frequency occurring in the sound signal.
Files are here: IO_SoundscapeOfColour.zip
In fact, there are 3 blocks for each channel, and the 3 of them should behave in the same manner. However, knowing that there would be a slight difference in calculations, there is a change in colour, and the blocks not always display the same tone.
The sound is read from a file in disc and there is spectrogram on top of the colour squares. To get the frequency of the sound, I used object fzero~, which does a straight forward frequency analysis. It outputs the central frequency of the sound and its amplitude.
With this is just a matter of doing some logic and maths to locate this frequency in the spectrum, and then turn it into RGB values, as follows.
This is the first part of an intent to control LEDs with sound and create Soundscapes. I am including the patches here, and a short video of the tests.
SOUND SCAPE project 