5 min read
Level: Thought experiment Real arithmetic, poetic meaning – no effect claims.
Imagine a single soft tone. 528 Hz, for example: the air in front of your ear moves back and forth 528 times every second. Now imagine that tone climbing, octave after octave, higher and higher, far beyond anything we can hear. Somewhere up there, after about forty octaves, the vibration becomes so fast that it reaches a range we know from somewhere else entirely: the range of visible light.
This is the idea of the light octave. It is a small piece of arithmetic – and a beautiful bridge between hearing and seeing.
One octave = twice as fast
In music, an octave is the most natural interval there is. Sing a tone and then the “same” tone higher: the higher one vibrates exactly twice as fast. 220 Hz, 440 Hz, 880 Hz – to our ear these are siblings, the same note in different heights.
So we keep doubling:
f × 2ⁿ
After 10 doublings, 528 Hz has become about 540,000 Hz – ultrasound. After 30, it is more than half a trillion hertz. After 40 doublings it reaches roughly 580.5 terahertz (580.5 × 10¹² Hz).
Where light begins
Visible light is an electromagnetic wave. Our eyes see wavelengths from about 380 to about 750 nanometres, which corresponds to frequencies of roughly 400 to 790 terahertz. Sources draw the edges slightly differently; NASA, for example, gives 380–700 nm as the typical range of the human eye.
A wavelength comes from the frequency with one simple step – divide the speed of light by it:
λ = c ÷ f
For our 528 Hz: 299,792,458 m/s ÷ 580.5 THz ≈ 516 nanometres. That is a clear, fresh green. A lovely coincidence: the tone that many people call the “love frequency” becomes the colour of leaves in the sun.
The ten Pure Soul tones as light
Every one of our tones lands in the visible range after 39 to 42 octaves. This is how the colours come out:
| Tone | Octaves | Light frequency | Wavelength | Colour |
|---|---|---|---|---|
| 174 Hz | 42 | 765.3 THz | 392 nm | violet |
| 285 Hz | 41 | 626.7 THz | 478 nm | sky blue |
| 396 Hz | 40 | 435.4 THz | 689 nm | red |
| 417 Hz | 40 | 458.5 THz | 654 nm | red |
| 432 Hz | 40 | 475.0 THz | 631 nm | orange-red |
| 528 Hz | 40 | 580.5 THz | 516 nm | green |
| 639 Hz | 40 | 702.6 THz | 427 nm | indigo |
| 741 Hz | 39 | 407.4 THz | 736 nm | deep red |
| 852 Hz | 39 | 468.4 THz | 640 nm | red |
| 963 Hz | 39 | 529.4 THz | 566 nm | yellow-green |
Something surprising happens here: the order of the colours does not simply follow the order of the tones. 396 Hz is red, 528 Hz is green, but 741 Hz – a higher tone – is deep red again. That is because each tone needs a different number of doublings. Light octaves do not form a rainbow from low to high; they form a circle, like the notes of a scale that keep returning.
Not physics of effect – a bridge of meaning
It is important to say this clearly: sound and light are different things. Sound is a pressure wave travelling through air. Light is an electromagnetic wave that also travels through empty space. Doubling a tone forty times does not turn it into light, and a 528 Hz tone does not “send” green into your body.
What the light octave offers is something else: a consistent, calculable language to connect a tone with a colour. People have been looking for such a language for centuries. In 1704 Isaac Newton divided the rainbow into seven colours – deliberately matched to the seven steps of a musical scale. Composers and painters later invented their own colour scales, and most of them disagree with each other. And research on perception shows that most of us intuitively link high tones with bright colours and low tones with dark ones; in 2011 researchers even found this link in chimpanzees.
So the light octave is one of several possible bridges. We like it because anyone can check it with a calculator.
Two colours for every tone
On our website, every frequency therefore carries two colours. One is the colour of the landscape in which we experience the tone – the deep forest green of 174 Hz, the sunlight on the stream for 528 Hz. The other is its light octave: the colour it would have if it became light.
You can hear and see both on the sound wheel of our Colour of Sound page: choose a tone, listen to it softly, and watch the room change colour.
A small invitation
Next time you listen to one of our tracks, try this: close your eyes and let the colour from the table appear in your mind – violet for 174 Hz, green for 528 Hz, yellow-green for 963 Hz. Nothing needs to happen. It is simply a way of listening a little more closely, with two senses instead of one.
Every tone carries a light within.
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