6 General problems related to the creation of color-tone analogies

Colors and tones differ in principle both as physical phenomena and with regard to their perception and are thus not subject to the same classification systems. When comparing spectral colors and musical tones, the following problems have to be taken into consideration. First, within the prism, colors have fluent transitions, whereas individual notes are clearly separated from each other on a theoretically constructed scale. Therefore, some points within the spectrum cannot be clearly defined by color names. Second, the boundaries of the spectrum cannot be clearly defined because the sensitivity of the human eye does not stop abruptly at the boundaries of the light spectrum, rather does so gradually. Third, the colors are unevenly distributed within the prism. The color red is dominant, which is why it should really be allocated several halftones on the musical scale. Whereas only minor color changes are perceivable in the wavelength range from approximately 600 to 700 nm, all the intermediate colors between red, orange, yellow, and green are to be found between 500 and 600 nm. The notes on a scale, by contrast, are evenly distributed. Fourth, the number of prism colors cannot be precisely defined as seven. Even in the eighteenth century, other subdivisions varying from five to eight colors were proposed.

The overtone series proved to be unsuitable as a basis for comparison for several different reasons. First, the sequence of tones progresses logarithmically and thus at changing intervals, whereas this is not true for the sequence of colors. Second, even within the first four tones, the same note is named three times. Third, there is an overtone series for every musical note, which means that there are numerous different overtone series, whereas the spectrum is not based on individual colors but on light as a whole.

In addition to the problems which have already been mentioned with regard to the design of analogies based upon spectral colors, there are two further difficulties regarding analogies based on the calculation of wavelengths.

First, in contrast to mechanical sound waves, light waves are electromagnetic waves, so that the transformation of tones into colors lacks any common physical foundation.

Moreover, the upward transposition of sound does not bring it into the range of visible light, but into the range of ultrasound.

Second, the progression of colors is arithmetical, whereas the progression of tones is logarithmical, which is why the two lack any comparable mathematical foundation.^[3]

In addition to the problems inherent in color-tone analogies that have already been described, a large number of further problems were recognized over time.

As early as the eighteenth century, objections were raised that could apply to any form of color-tone analogy. These objections are still valid today and demonstrate, moreover, that the many theories of the nineteenth and twentieth century with their individually slightly modified mathematical and physical procedures did not take into account the intense discussion that had taken place during the eighteenth century.

Thus, Jean-Jacques d’Ortous de Mairan, for example, mentioned the following aspects in 1737 and 1738. First, color harmony depends on habits and fashion, whereas the definition of consonances in music remains constant over time. Second, the effect of a color dissonance such as red with orange, for example, is less unpleasant than a dissonance in music such as a halftone. Third, colors blend to form a unity that can be analyzed — yellow and blue become green, for example; two tones, however, do not form the tone found in between, that is, c with d does not create D#. Fourth, the perception of a color is always absolute, whereas notes always refer to a tonic keynote.

Among other things, Hermann von Helmholtz discovered in 1854 that a melody maintains its basic character even when it is transposed a third higher or lower, for example. However, a painting loses its meaning if one replaces all its colors with those whose frequency ratio corresponds to a third.

Developments in music during the nineteenth and twentieth centuries led to further points of criticism with regard to the creation of analogies. For example, there is no predominance of major keys in atonal music and even less so of the C-major key, which had served as the basis for most analogies. As very differently structured non-European scales became known, the significance given to the numbers 3 – 7 – 12 in Western music systems was put into new perspective. Even the number seven in relation to the planets, which was taken as a sign of the reflection between microcosm and macrocosm, is no longer valid today.^[4]

Although the physical and perception-based prerequisites for color-tone analogies have been gradually proven wrong (which, however, does not stop many artists and theorists from still developing analogical models today), the fascination of artists with the transformation of tones into colors and thus with visualizing music is still alive today and has even increased due to the possibilities (such as parameter mapping) offered by contemporary computer technology.