The Cosmic Octave · Handmade crystal in Kreuzwertheim
What Frequency Is OM?
Ask this question online and you will find three answers: 432, 528 and 136.1 Hz. Each number has its own story. Here is where they come from — and the older, quieter answer behind them all.
First things first
The number you've seen
136.1 Hz. It's engraved on tuning forks. It's in a thousand video titles. People call it the sound of creation, the OM frequency, the note of the Earth.
Here is what it actually is — and it needs no legend to be astonishing:
It is one year, made audible.
The Earth takes 365.24 days to travel once around the sun. Turn that into a frequency and you get a number so small it means nothing to your ears — one cycle per year.
Now double it. Then double it again. Keep going — thirty-two times. You land on 136.10 Hz. A note. Slightly below C♯. Low, warm, entirely audible.
That isn't numerology. Doubling a frequency is what an octave is — the oldest law in music. A note doubled is the same note, one octave up. Do it to the Earth's orbit thirty-two times and you arrive in the middle of human hearing.
You can check the arithmetic yourself. It works.
The claim
Is it OM?
The story goes that this tone is OM. That the ancient Indians found it in meditation. That it's the keynote of the sitar and the tanpura — the note called sadja, the eternal tone.
The story has an author — and he is much closer to us than the legend suggests. His name is Hans Cousto, a Swiss mathematician, and he told it in 1978, in a book called The Cosmic Octave. It was his tuning-fork documentation that first wrote down the beautiful sentence about the ancient Indians, who were said to have "arrived at this tone through meditation."
It is a lovely image — and there is truth folded inside it. What the tradition handed down, though, was never a number. It was a way of singing, carried from voice to voice, teacher to student, for longer than anyone has been measuring sound. The numbers entered the story much later.
To hear the difference, listen to how Indian music is actually tuned.
The music
Why OM cannot have a frequency
Sa — properly sadja — is the first note of the Indian scale. The ground note. Everything else is measured from it.
But Indian classical music has no fixed reference pitch. No equivalent of concert A, no tuning standard, no number. The tanpura is tuned to the singer. A male vocalist might place Sa around C♯; a woman often about a fifth higher. Both are Sa. Neither is more correct.
Sa isn't a pitch. It's a position.
It works the same way in Western music. "The tonic" isn't a note — in C major, C is the tonic; in G major, G is. Any note can hold the role.
And OM itself is a syllable, not a pitch. When you chant it, it comes out wherever your voice lives. Measure a room of people chanting OM and you get a room's worth of frequencies, each with its own overtones. There's no note to match.
And this, quietly, is the most beautiful part of the whole story. OM was never bound to a single frequency — it sounds wherever a human voice lives, and for thousands of years it has belonged to every voice that carried it. The tradition left the pitch open. What Cousto offered in 1978 was an anchor of a very different kind: not a rule for the voice, but a tone drawn from the sky itself — the Earth's own year, raised into hearing. The tradition kept OM boundless. The mathematician gave it a home note.
The other two numbers
Then what about 432 and 528?
If you've searched this question, you've met two other numbers. They come from somewhere else entirely.
432 Hz isn't about OM at all — it's an argument about concert pitch. A = 440 Hz was agreed internationally in 1939 and later written into ISO 16. Verdi preferred the French standard of 435 and once remarked that 432 was "slightly better" — a composer's taste, recorded in a letter. Comparisons of 432 and 440 have found small, gentle differences, and many listeners find 432 a shade warmer — a breath lower. There are musicians who tune this way out of real conviction, and it is a lovely debate to follow. It is simply a different one: a question of where to anchor an orchestra, not of what OM is.
528 Hz belongs to the Solfeggio frequencies — and their story does have a genuinely old root. The syllables they are named after, ut, re, mi, come from a real medieval hymn to John the Baptist, the same one Guido of Arezzo used a thousand years ago to teach singers their scales. The numbers, though, are young: they were derived in the 1970s by Joseph Puleo, who read them out of verse numbers in the Book of Numbers, and made famous by Leonard Horowitz in 1999. Medieval singers tuned by ear and by voice — the idea of counting a tone in hertz did not yet exist. The hymn is ancient. The hertz values are not — and if an older record of them exists, no one has yet produced it.
Science has, in fact, taken a look at OM and the numbers. A randomised trial published in 2025 had patients with high blood pressure listen to OM chanting — tuned, as it happens, to 528 Hz — for fifteen minutes a day. After a month, the listeners showed calmer readings: a lower pulse, lower blood pressure, better sleep. But notice what the study compared: chanting against no chanting — not one frequency against another. Which makes it evidence for the oldest claim in this whole story, and the one that never needed a number in the first place: the practice itself.
The older answer
What OM actually is
All of this is a footnote to something much older and much more solid.
In the Indian tradition, nada is the primal sound, and Nada Brahma means: the world is sound. OM is the syllable that holds that idea. It opens and closes practice, it sits at the head of the mantras, and it has done so for thousands of years.
Nada Yoga — the yoga of sound — is a real, old, continuous tradition. It teaches listening as a practice: following a tone until it thins out, and noticing the exact moment you can no longer tell sound from silence.
OM never asked for a number. Long before anyone could measure a vibration, the syllable was already doing its work — in the chant, in the long hum, in the stillness that follows it.
The power of OM lives in the practice.
Three thousand years of voices have carried it that way — one breath at a time.
Pythagoras · Kepler · Cousto
The music of the spheres, made audible
The idea that the cosmos is musical is genuinely ancient. Pythagoras discovered at the monochord that the intervals we find beautiful correspond to simple whole-number ratios — the octave 2:1, the fifth 3:2, the fourth 4:3 — and concluded that the same order must govern the planets. Musica universalis. The music of the spheres. The line runs from Pythagoras to Plato, to Ptolemy, to Boethius, and to Kepler, who in Harmonices Mundi (1619) found the ratios of the planets' orbits sitting remarkably close to musical intervals.
And every one of them said the same thing about it: you cannot hear it.
That was never the claim. The music of the spheres was an order grasped by the mind — a mathematical harmony, not a sound. For two and a half thousand years, nobody suggested you could put your ear to it.
Then in 1978 a mathematician doubled a planet's orbit until it entered the range of human hearing.
Cousto didn't rediscover an ancient sound. He did something nobody had done before: he made the inaudible audible.
He did it with arithmetic anyone can check — and in doing so he gave the old harmony something it had never had in all those centuries: a voice. When you strike the Year tone chime, that is what rings through the room. The planet's long circle, present in the air, for as long as the crystal carries it.
Twenty-five centuries of philosophers heard this music only in their minds. You get to close your eyes and listen.
The tone itself
Listening to it
Enough of the numbers — here is the tone they all circle.
Strike it and let it ring all the way out. The interesting part isn't the strike — it's the long decay, and the moment near the end where you stop being able to say whether you're still hearing it or remembering it. That threshold is where Nada Yoga has pointed for centuries, and you don't need to believe anything to find it.
The chime sings the year-tone a few octaves above 136.1 Hz — the same note, carried higher. A tone loses nothing when it climbs an octave; it keeps its character and changes only its register.
From the workshop
Hear it for yourself
Year Tone Chime — 136.10 Hz
Tuned to the Earth's year, raised thirty-two octaves. In the Cosmic Octave this tone is known as the Om tone — the name Hans Cousto gave it in 1978. Each chime is made and tuned by hand; the long, clear decay is the material doing the work.
See the Year tone chime →Questions
OM frequency FAQ
Does OM have a frequency of 432 Hz?
No. 432 Hz belongs to a separate debate about concert pitch — A = 440 Hz was standardised in 1939, and some musicians prefer 432 as a matter of taste. It has no connection to OM. OM is a syllable, and its pitch depends entirely on the person chanting it.
Is 136.1 Hz the OM frequency?
136.10 Hz is the Earth's year translated into the audible range by doubling it 32 times — that calculation is exact and checkable. Calling it "the OM tone" is a name given by Hans Cousto in 1978, not a property of OM. Indian classical music has no fixed reference pitch, so there is no OM frequency for it to match.
Is 528 Hz the frequency of OM?
No. 528 Hz belongs to the Solfeggio frequencies, assembled in the 1970s by Joseph Puleo through numerology applied to the Book of Numbers. They are not ancient, and they are not connected to OM.
What note is 136.1 Hz?
Slightly below C♯. In the Cosmic Octave system it is referenced to a concert pitch of A = 432.1 Hz — which is why you will sometimes see 432.1 listed next to this tone. That number is the tuning reference, not the pitch of the tone itself.
How is the 136.1 Hz tone calculated?
Take the Earth's orbital period: 365.24 days. Express it as a frequency — one cycle per year. Then double that frequency 32 times. Doubling is what creates an octave, so the note keeps its character while rising into hearing range. The result is 136.10 Hz.
Why do people say OM is the sound of creation?
Because in the Indian tradition nada is the primal sound and Nada Brahma means "the world is sound." That is a genuine, ancient idea — and it is about the syllable and the practice, not about any particular number of hertz.
- Hans Cousto — Die kosmische Oktave / The Cosmic Octave (1978) and the Cosmic Octave tuning fork documentation: the octave law, the earth-year calculation, and the sadja / OM attribution discussed above.
- Johannes Kepler — Harmonices Mundi (1619): orbital ratios and musical intervals; the classical position that the music of the spheres is grasped by the mind, not the ear.
- Tanpura & Indian tuning systems — on the absence of an absolute reference pitch: Sa is set by the singer, not by a standard.
- ISO 16 / concert pitch — A = 440 Hz agreed internationally in 1939; Verdi and the French diapason normal at 435 Hz.
- Solfeggio frequencies — Joseph Puleo (1970s) and Leonard Horowitz, Healing Codes for the Biological Apocalypse (1999).
- Bhoot et al., Annals of Neurosciences (2025) — "Effect of OM Chanting of 528Hz Frequency on Heart Rate Variability, Psychological Wellbeing, and Quality of Sleep in Patients of Hypertension: A Randomised Controlled Trial": chanting compared against no chanting — evidence for the practice, not for the number.