The Sound of Color

TL; DR: This is an exploration and visualization on how sounds and colors could interact. There are two main points: one in which we explore the relationships between two sounds (keeping one fixed reference point) as proportions on the color wheel.

The second, less sound experiment (pun intended), we try to convert pure colors into equivalent musical notes.

That's it in a nutshell! Enjoy!

What am I watching?

You are seeing a color wheel, but I assume you already know that. Have you ever wondered why colors are traditionally laid down on a circle, and that said circle seems to close itself? Well, that's complicated.

Color is, as you know, light. But not all light appears to us as color. Our eyes can only perceive a very small fraction of the electromagnetic spectrum. Every light wave, like any other wave, can be characterized by one of its two essential components: its frequency (i.e. the amount of oscillations it makes in the space of one second), or its wavelength (the distance between each peak and valley of the wave).

Within this continuum, we call infrared any electromagnetic wave which is too slow (or long) for our eyes to perceive, because on that lower end of the spectrum is where light starts appearing to us as red. Increasing the frequency, we get within the small range of all (humanly) visible colors; then, at some point, we perceive the violet tones and finally the wave fades back into invisibility—being too fast (or short) for our eyes to perceive—in what we call—you guessed it—the ultraviolets.

A linear representation of the electro-magnetic spectrum with a highlight on the visible light

So, you might be thinking: that sounds a lot like a line, rather than a circle. How would the two ends meet?

How do the two ends meet?

To put it bluntly, it's a trick of our perception. Well… like everything else, I suppose. The thing is: our brains are surprisingly good at pattern recognition. That seems to be our primary meaning-making mechanism: we do not care about things in isolation, but only about relationships; things that do not form regularities, or orderly perceptions, we call “noise” and we filter them out very efficiently from our perceptual data.

Incidentally, that is why we like very regular shapes like squares and circles; why we think simmetry is beautiful; why we invented (or discovered, depending on your school of thought) geometry and math.

So, what is this relationship that makes the ends meet? It is indeed the simplest mathematical relationship of all times: 2:1.

The visible spectrum that I mentioned above is in fact a very small slice of the whole spectrum, in which the higher end is about twice the wavelength of the lower end (between around 380nm and 700nm).

It is, you might have noticed, in fact a little bit less than twice, and indeed if you switch the Show visible spectrum option (which shows a more accurate representation of the physical spectrum of “pure wavelengths”—we'll get to that, don't worry), you will see that there is an invisible gap and the ends do not truly meet.

Notice how Magenta appears as a combination of equal amounts of blue and red light Bb3cxv , CC BY-SA 3.0 , via Wikimedia Commons

However, our eyes bridge that gap by making up the color commonly known as magenta, which is how we make sense of light with red and violet components of equal intensity: and thus a smooth transition between the two ends appears.

Get to the point! What about sound?

Sound, too, is a wave—albeit of a different kind—and interestingly, there too does the relationship 2:1 have a very peculiar significance to the human brain. We call that relationship the octave.

For example, in our western musical system, you might have heard of our cycle of notes typically starting from C and going back to C. The “physical distance” between these two “C”s is, indeed, double the frequency. These notes, while objectively of different frequencies, sound to our ears as essentially of the same quality. In fact, if you typically ask a man and a woman to sing the same note, they will do so one octave apart.

This fact is not cultural, and is basically perceived in this way universally, across human cultures. You can say that, in a sense, all music happens within the circle of the octave.

The way you divide the circle into discrete notes is what makes an essential and distinctive part of the musical system of each culture. However, there are certain other simple mathematical ratios which are most often used cross-culturally (you can learn, experience, and experiment more with them on the Representation of 8th Overtone Overtones spiral ).

So we wondered: what if we tried to visualize on the color wheel the same proportions that we usually find harmonious in music? That's how this experiment was born.

Wait, don't go! I've heard each color corresponds to one sound. Explain please.

We do explore this claim too: you can do so by clicking over the Absolute mode .

You'll see a few things change: for one, many of the options will disappear, as they are no longer relevant. Most importantly, the color wheel will be in the Visible spectrum mode.

Let's look at the difference between the two: as we have mentioned above, in theory, a pure electromagnetic wave of a certain frequency or wavelength, such as one emitted by a laser, appears to our eyes as a specific color.

Red lasers: 660nm, 635nm; Green lasers: 532nm, 520nm; Blue lasers: 445nm, 405nm 彭嘉傑 , CC BY-SA 3.0 , via Wikimedia Commons

That is what you see in the Visible spectrum mode. Starting from invisible, infrared wavelengths, you can follow clockwise as the wavelengths become shorter and we see all the rainbow colors, until we fade back into invisibility on the ultraviolet wavelengths.

However, life is almost never as pure as physics, and the light which come across is oftentimes not a pure wave: it is instead a mix of many waves, which gets interpreted by our eyes as being of one color. As such, a yellow color might be the result of very different mixtures of red and green light.

In contrast, the hue wheel which we display by default is a smoother representation of the colors using the HSL Color Model, which, in a nutshell represents the way our eyes perceive the smoother transitions between colors when adding them together. And that's why magenta is there, as we have mentioned above.

In the HSL/HSV system, hues are arranged radially to more closely align with the way human vision perceives color-making attributes. (3ucky(3all , CC BY-SA 3.0 , via Wikimedia Commons

To get back to the question of translating one color into one sound, the theory goes like this: each pure color is a wave with a certain frequency. The frequency is obviously very high, but what would happen if we took that frequency and slowed it down until it reached the range of audible, or even musical, frequencies? Keeping in mind what we learned about the octave, since the significance of the sound doesn't change with each circle doubling its frequency, we should get an equivalent sound that we can play and sing.

In Absolute mode , this is what you see: you can play around and you'll see on the information box the note which has been calculated through this process, halving the frequency of a given color about 40 times in order to get to audible ranges. You can see its wavelength on the top right corner, the closest note in our 12 Tone Equally Tempered System using the Stuttgart Pitch Reference; and at the bottom how many cents does it actually diverge from the reference note.

Representation of the propagation of a sound wave through a medium CDang , CC BY-SA 3.0 , via Wikimedia Commons

We loved if all of this were true, but we want to be honest with you, and even though we wanted to explore this through our visualization, this theory has some fundamental problems: for one, as we mentioned, since the same color can be made of multiple combinations of waves, we could perhaps always go from an audible pitch to a specific color, but not the other way around.

Secondly, even though we call both of them waves, sound and light are two essentially different kind of waves: the former are compression waves, while the latter are electromagnetic waves. As such, acoustic waves propagate by displacing matter (like waves on a lake, or seismic waves) and thus need a medium, while electromagnetic waves do not need a medium. So it's not like if you actually slowed down electromagnetic waves, you'd all of a sudden hear them, alas.

Thirdly, light waves and sound waves have completely different speeds and interact with mediums in a different way. In a nutshell, you can double the frequency of a sound until you get in the range of the frequency of light, but the resulting wavelength will not be the one that you had expected. Simply, the math just doesn't add up.

But play with it and have fun! Also, if you are synesthetic, let us know if the relationships correspond at all to the ones you perceive. We'd love to hear from you!

3-limit

⁴/₃

Perfect fourth

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