In 1675, Sir Isaac Newton suggested a correlation between the bands of color from a prism and the notes that can be played on a single string. Fifty years later, Louis Bertrand Castel theorized about an "ocular harpsichord" that he believed could "not merely give a simple impressionistic idea of sound in color, but would really paint sounds by a precise and natural correspondence between color and pitch," even to the point that a "deaf listener could enjoy music that was originally written for the ear." Bainbridge Bishop, in 1893, invented a color-organ that related different hues to the different notes in an octave.

These and many other color-correspondence theories relate colors to specific pitch-classes within an octave (all the Cs in different octaves, for example, would be the same hue). If sound was to be related to color, however, it seemed logical to me to create a translation of sound waves into light waves by relating the visual spectrum of light to the audible spectrum of sound. This approach avoids "artificial" cultural constructs such as music theory, or any particular meanings associated with colors.

While many of the color-correspondence theorizers were after a "true" relationship—in essence, the relationship—between sound and color, I fully acknowledge that my spectrum-to-spectrum relationship is simply a logical and interesting exercise.