Neil Harbisson was born with achromatopsia – a rare visual condition that results in total color blindness. To him, the world is a constantly dreary plane of grays, black and whites. But since 2003, the eccentric artist has had an antenna poking out of his distinctive bowl-cut hairdo, which allows him to “hear” colors.

His head-mounted antenna is able to detect the wavelengths of light reflected off whatever is in front of the sensor and then convert them into sound, with different wavelengths corresponding to different sound frequencies. The Belfast-born, Catalan-raised artist's antenna is permanently attached to his skull and delivers the sound waves to his inner ear through bone conduction.

Purples and indigos are perceived as a high-pitched bleep, with the colors becoming lower pitched as the spectrum shifts from blues to greens, then yellows to oranges, and so on. You can see in the table, below, how each color is “translated” into a sound in the antenna and mind of Harbisson.

^{How Harbisson's antenna portrays color wavelengths in Hertz (left) and musical notes (right). If need be, he can switch his antenna on or off. Image credit: Townsend87/Wikimedia Commons.}

[H/T: Discovery News]