Other people see sound as color—it's called "Sound -> Color Synesthesia," and it sounds intense as all get out. I've known a couple of people whose brains worked like this—their musical hearing went beyond perfect pitch into a visual realm. It left them able to hear notes and harmonies in a unique and mystifying (to me) way.
This camera, called "Audible Color," is also a synesthete. It's a musical instrument designed by Hideaki Matsui and Momo Miyazaki that "reads" colors on a spectrum that assigns various colors to various notes. It's a nifty way to generate (and observe) music, and the melodies it creates are soothing and unpredictable.
From Matsui's website:
Audible color is an audio-visual instrument. Sound is generated based on color detected by a web cam connected to a computer. Red, green and blue correspond with certain music notes. When the colors are mixed, the resulting secondary colors produce different notes. The size of the colors influences the volume and frequency of the notes played. Color detection and sound generation were created and are controlled using Processing code.
If you've played a game like Flower or Sworcery, where musical tones are generated by touching things in the environment, you've probably seen something similar. The world is made into natural music, and the resulting melodies are just as beautiful as notes on a page.
Audible Color [Hideaki Matsui, thanks G.A.!]