THE LANGUAGE OF COLOUR
Let us know examine the different categories that we find when combining characteristics of sound with characteristics of colour. To do so, we will take some time to dive into colour theory in order to define the qualities of colour that we will use to draw parallel lines to those of sound.
Colour is among the strongest stimuli that our brains receive from the outside world.
Colour is also complex. Since Isaac Newton, scientists have been developing theories of colour vision, and artists have been proposing principles for its effective use. One of the most important assumptions made about colour relates to its trichromatic nature. Under this assumption, uniquely specifying a particular perceived colour requires the use of three terms, such as hue, value, and saturation.
Hue is the principal way in which one colour is distinguished from another. Describing and managing hues is generally taken to be the central problem for colour theory. The very language we use to denote colours is associated primarily with their hues.※
A hue can be referenced by its angle around a colour wheel: for example, red at 0, yellow at 60 degrees, green at 120, blue at 240, and purple at 300. In a well- balanced colour wheel, complementary colours appear at 180 degrees opposite each other. Numerous colour wheels have been defined. They all share the objective of making the relationships among hues more accessible. Because hue is a continuous gradient, naming and distinguishing among hues is some what arbitrary. Johann Wolfgang von Goethe (1749-1832) and Arthur Schopenhauer (1788-1860) spoke of six distinct hues, Wilhelm Ostwald (1853-1932) of eight, Albert Henry Munsell (1858-1918) of ten.※
Saturation describes how pure a particular hue is. It is also referred to as the intensity, strength, or chroma of a colour. Reducing the saturation of a particular hue, while maintaining its value, has the effect of adding white pigment, producing what artists call tints.
Value is the quality that differentiates a light colour from a dark one. It is also referred to as lightness. A particular colour moves toward black by a reduction in its value. Low-valued colours are less visible than ones with higher values. Decreasing value while leaving saturation alone has the effect of adding black pigment, producing what are referred to as different shades.
The mediation of crossmodal equivalence
What is it that mediates between light and sound? To say that subjects match auditory and visual brightness may be correct, but even if it is, we do not know what IT IS that brings these two dimensions together. In Aristotelian terminology, we are asking, what is "το κοινόν αισθητήριον" or "sensus communis"? It might be a common, innately given neurophysiological code: certain spatiotemporal patterns of nerve impulses that underlie both auditory and visual brightness for example. ※
A DIFFERENT VIEW ON THE ONTOLOGY OF SOUND AND COLOUR
Just as colour can be defined by three parameters—frequency/hue, amplitude/value, and overtone or timbre/saturation—musical tones share similar attributes. Exploring potential parallels between these dimensions and those of colour has intrigued scholars over time. One enduring connection between colour and music involves attempts to match specific hues with particular tones, known as pitch-luminance correspondence. Sir Isaac Newton famously linked the seven colours he identified (red, orange, yellow, green, blue, indigo, and violet) with the seven notes of the Western scale (C, D, E, F, G, A, B). However, the division of the visible spectrum into seven colours is somewhat arbitrary. Some speculate that Newton perceived seven colours in the rainbow due to the seven natural tones in the musical scale.
Various writers have put forward alternative mappings. Despite over a dozen different proposals found in historical literature, there is scant consistency among them.※
In this section I would like to shed light onto the ontological point of view when comparing music with colour, or eventually sound with light. The reader might be already familiar with the fact that both sound and light from a physical/scientific point of view are both waves. However, there is a crucial difference. Sound waves are purely mechanical waves, meaning that for them (sound) to be transferred, a medium is required. Light carries a dual identity -an axiom from classical quantum mechanics. It is a wave and a particle at the same time. Being an electromagnetic wave, (and not a classical one) light needs no medium to be transferred.
There are many problems with these tone-hue correspondences. Our experience of musical notes is closely related to their physical existence. Small numbers of oscillations per second are perceived as deep notes. As the number of oscillations increases, tones ascend in pitch. This increase in frequency yields a predictable pattern, where in doubling the number of oscillations produces the same note an octave higher. However, colour lacks a definitive lowest or highest perceived hue, and alterations in the number of oscillations don't consistently alter the perceived colour. While certain changes in frequency along the colour spectrum are easily detected, others may go unnoticed entirely. In a chord blending multiple notes, their individual identities remain discernible to the ear. Conversely, when blending colours, their identities are often obscured to the eye.※
Mappings that are very direct will, in general, use too many hues and will quickly appear trivial and repetitive. But there are other possibilities. Colour is defined by three parameters, as are musical sounds. The interactions of these sets of parameters produces nine possible one-to-one mappings, and of course numerous others could be contrived through combi- nations of parameters. And beyond these there are such musical parameters as tempo, interval, and mode and such visual ones as texture, shape, and movement.
Additional challenges emerge with analogous mappings. Following the selection of a tuning system (e.g., Pythagorean, equal temperament), musical tones precisely align with only one specific frequency in Hz. Conversely, concerning colors, 405 THz is perceived as red, as are 410 THz and 420 THz. Upon exposure to these colour patches concurrently, individuals often distinguish three distinct hues of red. Consequently, while the sound continuum divides into discrete points (i.e., tones), the colour continuum fragments into overlapping regions (i.e., hues). One might contend that a tone at 445 Hz closely resembles A (440 Hz), which is likely the case. Nonetheless, the crucial distinction arises: the note ceases to be A in terms of frequency, whereas hues at 405, 410, 420 THz remain red.※
"For the artist Paul Klee (1879-1940), who was also a musician, colour held a mysterious, irrational, and evocative quality. He believed it could embody countless shades, of similar nature to the versatility of musical tones. Yet, he approached the idea of correlating colour and music with caution, wary of creating mappings that were overly literal or direct."
Although one can draw an analogy between pitch and hue on a cognitive or abstract level, suggesting a correlation in the relative positions of auditory and visual stimuli along their respective unisensory dimensions, there is limited empirical evidence affirming the presence of perceptual 'resonance' or unification resulting from the accurate structural alignment of stimulus dimensions. In other words, aligning the dimensions of pitch and hue does not inherently result in any perceptually evident correlation based on the perceived similarity of the component stimuli.※
