What Colour is the Blues?

Musicians, artists and scientists have long tried to find relationships between sound and light, between music and colour, without much success. Here we review the history and look for new ways to explore this fascinating and deep subject.

Science

Let’s briefly get some technical background out of the way. As we all know, our perception of light and sound is due to the conversion into electrical signals of energy incident on our eyes and ears which is carried by waves. There are fundamental differences between the two kinds of waves, but each is characterised by a frequency, or a sum of a set of frequencies. For light, we register the frequency as a colour, for sound, a pitch. It’s natural therefore to consider whether there is some kind of relationship between a colour that we perceive, for example yellow, and a pitch that we hear, for example middle C.

History I

Most histories of this topic begin with Newton who, stuck at home due to the plague, got very interested in the way certain shapes of glass refract white sunlight into a rainbow of component colours. Drawing on ideas from Greek philosophers he attempted to relate this spectrum to the notes of a musical scale. It is for this reason that today that schoolchildren are taught that a rainbow has seven colours. Scales in western music (so-called diatonic scales) have seven notes, and Newton believed there was a deep harmonious correspondence between notes and colours.

Newton's colour wheel

This work was continued by others, most famously by the Russian composer Scriabin. He decided that each note on the musical scale should correspond to a hue, based on a process of mapping the colour wheel to a progression of notes in a circle of fifths. Presumably because a diatonic scale can be generated by a circle of fifths, so that the spectrum is like a musical scale. According to his “Clavier a Lumieres”, the note C is bright red, D is yellow, and so on.

 Scriabin's Clavier a Lumieres. Yes, I know.

However, there is a reason why Newton’s laws of motion are of central importance even today, whereas his theory of colour and sound has been largely forgotten.

Failure of simple mappings

Does middle C really sound red, while a whole tone up sounds yellow? Of course not. If we mix the spectrum of visible light we get white, which we think of as just another colour, whereas if we play all the notes of a piano at once we get an awful noise. When we play a musical scale, we get a very different feeling depending on the order in which the notes are played (usually called a melody) whereas presenting colours in different sequences produces no such effect. Playing two notes together produces an entirely different auditory experience depending on whether the notes are consonant (for example a perfect fifth) or dissonant (for example a chromatic), while playing two colours together produces a new pure colour which has a similar perceptual status to the original unmixed colours.

This leads to the other important observation that we are sensitive to absolute colour frequencies (we will detect a frequency of around 340 THz electromagnetic radiation as “pure red”), whereas our ears are sensitive to frequency differences. Most people will not be able to identify an air pressure oscillation of 261Hz as “middle C”. However, playing the white notes on a keyboard with the right hand, while holding down the C key in the left hand, produces the familiar “C major scale”; whereas playing the same notes while holding a D key produces the “D dorian scale”, which produces a very different sensation for the listener.

The reasons behind these key differences arise from differences in physics, on our sensory apparatus, and on cultural and psychological factors. For the present, let us just recognize that such mappings don’t work.

History II

Within the 20th century’s creative explosion in art and music, some artists sought to connect the two explicitly. The most famous being Kandinsky, who claimed to experience synaesthesia, seeing colours and forms when he heard music. This he reproduced in some of his abstract paintings. For him, yellow was "an intense trumpet blast by its nature springing from the painting” while blue, "a celestial sound that touches the depths." Further he related geometrical patterns, such as a series of black lines, with the beating of a drum, and so on.

 Kandinsky's Composition 8

In a similar vein, the Danish artist Wilfred sometimes interpreted music using his “Clavilux” machine, which projected shapes whose colours were controlled manually based on his intuition on listening to the sounds.

We have talked about colour hue in relation to pitch or timbre, but we should not forget that colour has a brightness and sound has a volume. The quantitative relationship between the two has been studied, though even here the researcher Marks has noted “In some fundamental sense, the similarities between pitch and brightness and between loudness and brightness are personal, internal and subjective.” Similarly, attempts to link colour saturation with the timbre or “richness” of a tone have not proved convincing. And finally we should note that there is some indication that warmer colours are perceived to be associated with faster tempos, cooler colours with slower.

[A thorough review of the history can be found here.]

Colour and sound perception

Kandinsky’s association of the colour yellow with the sound of a trumpet is interesting. Although the specific wiring of his brain may well have created auditory hallucinations, the association doesn’t seem arbitrary or specific to him. Yellow does seem brassy. This association is somewhat undermined by Kandinsky, at other times in his life, referring to the sound of trumpets as “scarlet” or “light warm red” but it’s still worth noting.

A key difference between Kandinsky and Scriabin is the association of colour with the quality of a sound, rather than a pure pitch. In other words, the timbre of a trumpet, the spectrum of frequencies in a single note, has a “bright, joyful” sound, which we can relate to a bright, joyful colour.

This seems much more promising than the earlier work, in that we are attempting to relate the emotional effect of the stimuli rather than some arbitrary physical quantity. However, it breaks down as soon as one attempts to go beyond these fairly crude associations. Do the yellow jackets of security guards, or the playing of Louis Armstrong, always inspire “joy”? We are in the complex world of the psychology of colour and music in context.

We sing the blues when we feel blue. The blues scale, whatever that actually is, weaves major and minor intervals to create a powerful palette of expression of sorrow and joy. We say we feel blue when we are sad (minor key) but we retain some positivity (major key) otherwise we would say we feel we are under a black cloud. Why the colour blue? We don’t mean bright blue, in this context, nor do we mean royal blue or sky blue. When we have the blues we think of the dreary blue colour of a rainy day, which is only blue in movies. Or we think of the neon blue of a dive bar at night. There is no frequency for those shades of blue, because those shades only exist in our minds.

Colour and emotion

While it’s true that certain colours seem to have fixed associations, such as red for danger and white for everything/nothing, our emotional response to colour is of course highly culturally conditioned.

We have Robert Plutchik’s Wheel of Emotions, with red associated with rage, shades of green trust and fear, purple disgust and so on.

We have sepia associated with nostalgia, blue or green the future, red with romance.

And different colour schemes are used in movies to create different emotional states. Monochromatic: historical (black & white), change of context (yellow for Mexico, bluish for US). Palettes with similar colours (“analogous”) creating naturalistic scenes, while vivid complementary colours creating artificial or unsettling scenes. Splashes of primary colour creating surprise or shock.

 Hitchcock's Vertigo: Complementary red/green as the colours of obsession

Music and emotion

Clearly with sound there is vastly more freedom to create nuanced emotions than with colour alone. We can touch on western harmony, with our response to major vs minor, to ascending scales vs descending scales, on tonality vs atonality, consonance vs dissonance, timbre, rhythm. The envelope of a single note (ADSR) or better the way an acoustic note is played by the musician, can in itself produce an emotional effect, and this effect may well be different for different listeners.

Of course we can explicitly identify the emotional content of certain musical forms, typically cliches, such as sad songs in a minor key (blue), bombastic orchestral works (red), military bands (yellow), bubblegum pop (pink), death metal (black). But how do we go beyond cartoonish associations of music and colour with broad emotions?

Colour, sound and form

We have made no mention so far of shape. While our ears can of course interpret a three dimensional soundscape, they have orders of magnitude less spatial resolution than our eyes. So unless we wish to confine ourselves to infinite colour fields, we do need to take account of the shapes and patterns. Indeed, there is probably more direct association between sound and shape than there is between sound and colour.

For example, dry (unfiltered) electronic sounds with few harmonics and sharp temporal edges suggest simple polygonal shapes with sharp edges, while wet (reverbed) sounds suggest amorphous, evolving shapes.

And a shape implies more than one colour, perhaps most fundamentally two complementary colours. And this further complicates our discussion, since our perception of colour in one area is affected by the colours of adjacent areas. For example, a coloured shape which appears orange against a dark background will appear brown against a bright background.

But perhaps this gives us a clue to the way forward. In our discussion above, we commented that the absolute pitch value of a note carries far less meaning than the pitch relative to other notes in a series or played concurrently.

Playing a note one semitone above middle C is unremarkable. But introducing that note into a melody of rising and falling notes from the C major scale most certainly stands out. The colour red is no more remarkable than any other colour. But introducing that colour in the form of a flower into to a scene of rolling green hills most certainly stands out. How many poppies do we have to add before the scene becomes a field of poppies? How many sharps do we need to add before C major becomes A major (ok, that’s easier to answer).

The key observation is that, in absolute terms, no individual note carries any more meaning than any other note, just as no individual colour carries any more meaning than any other colour. Even colours with strong associations, like bright red (danger) can invert those associations (luck or love) depending on the context.

What Colour is the Blues?

We talked about the blues scale above. A little vaguely as we didn’t specify exactly what it is. Not so easy to pin it down, it turns out. If you really press someone who has played enough, they will probably tell you that it consists of all the notes the instrument can play, which doesn’t seem particularly helpful. What they mean, of course, is that it isn't rigid. Any note can be part of the scale, but it is the emphasis of some notes over others that makes it the blues, what gives it the feeling of the blues.

It’s no coincidence that the go-to instruments for blues players are guitars, old pianos, harmonicas. Less commonly, harpsichords and piccolos. The aim is for a loose, expressive sound that can be shaped, distorted, sometimes discordant, sometimes concordant. It’s perhaps no coincidence that the form a good means of expressing our feelings: emotions are messy, and so is the blues.

What emotions are being conveyed is another matter and, indeed, the great thing is that listeners project their own onto the music. In the same way, the Hitchcock complementary red/green colour palette above is emphasizing obsession, because that is the subject of the film, whereas the same colour palette is used in the film Amelie to imply a intense romantic nature.

But in all cases above the emotions are intense. Not serene, for sure. Music we associate with serenity, perhaps Satie or certain minimalist works, can be powerful but calming and stabilizing. Philip Glass’s work Floe is aptly named. We might think of icefields, seascapes, rolling hills, sand dunes. Those colour palettes are often called analogous.

The point is that perhaps it doesn’t actually matter what the absolute values of the colours are, or what the absolute values of the notes are, as much as the relative values of adjacent elements and what shapes they create.

Debussy and Monet

In the early 20th century, the tonality of jazz music was similar to classical music and very different to what we think of as jazz today. The only significant departure was the incorporation of “blue” notes like the flattened 3rd. Much of the rich palette of modern jazz, from heightened or diminished chords, to use of modal forms, can be traced back to the radical innovations of Debussy.

Debussy was of course an impressionist composer, explicitly inspired by the contemporaneous impressionist art movement (though he strongly disapproved of the classification).

We can identify numerous parallels between Debussy’s music and the paintings for example of Monet but we here confine ourselves to use of colour.

Houses of Parliament after Sunset, by Monet

Some of the novel chords introduced by Debussy

One of the characteristics of Monet’s work, and of impressionism in general, was the use of vivid complementary colours to capture the impression of light playing across a surface. Unlike later art, hues are not stretched so far that they are wholly artificial. We still sense the original colours of the natural scene, but they have been tonally enriched and so our sense of calm at this tranquil scene is at the same time retained and imbued with a sense of joy.

Similarly, Debussy’s stretching of harmonies did not go so far as to lose sense of the original tonality, unlike that of later composers. He tonally enriched his C major chords by adding notes which do not strictly belong to the primary tonality of that key. We still recognise the chord, but the sensation is heightened and broadened.

Conclusion

We believe that one possible way to link colour and music is to exploit the parallels between expanding the colour palette from analogous to complementary, and expanding the musical palette from strictly tonal to incorporate additional tonalities.

We plan to explore this direction in our next audiovisual work.