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Schumann 3rd Harmonic
A steady low hum, one tone to each ear, with a pulse a little quicker than the second harmonic’s. The resonance behind the name measures near 20.8 Hz, which is nominally just inside the range of human hearing and in practice out of reach: down there it takes enormous sound pressure to register anything, and a small speaker produces none of it.
Ready to play
Stack this under rain or a fire, keep the blend, and play it with your screen off. Slo, on iOS, Android and Mac.
What you hear instead
The hum sits low, at 215 Hz, and holds one level for the whole loop with nothing in it that arrives or fades. Every other Schumann harmonic file here hums within a few hertz of that, so choosing between them is a question of pulse speed rather than pitch. The 20.8 Hz figure lives as the difference between the tone in your left ear and the one in your right, which makes it something your hearing assembles rather than something in the room.
Take the headphones off and most of it goes. Both ears then receive both tones, the pulse largely disappears, and the hum carries on alone.
Twenty hertz is a threshold, not a promise
The usual figure for the bottom of hearing is 20 Hz, which makes 20.8 look as though it should just about work. Sensitivity collapses at the bottom of the range, so a tone that low has to be played very loud before it registers at all, and at that point it is felt through the chest as much as heard. Reproducing it needs a driver big enough to shift a lot of air, and a phone speaker is a few square centimetres of cone. Whatever your laptop is giving you, it is not the third Schumann mode.
The phenomenon behind the number is real enough. Schumann resonances are standing electromagnetic waves in the cavity between the Earth’s surface and the ionosphere, kept going by lightning around the world and measured routinely since the 1960s. They are not sound, no microphone captures them, and they carry no established meaning for listening.
What to do with it
No clinical guideline or systematic review backs the health claims attached to these tones. Play it if you like a low, slowly pulsing sound; do not expect it to do anything. The Schumann Fundamental page covers the binaural-beat evidence in more detail, including a review of fourteen EEG studies that reached no clear conclusion.
For a single pitch with no beat, the 174 Hz tone is the deepest on the site and the 285 Hz tone sits in the middle. Everything else is on the sound library index. To soften the tone, open the Schumann third harmonic and gentle rain blend in the free sound mixer.
Frequently asked questions
Is 20.8 Hz audible?
Not in any practical sense. It sits at the very bottom of the hearing range, where sensitivity is poor, and consumer speakers and headphones produce almost nothing there.
What am I hearing, then?
A low tone in each ear, the two differing by 20.8 Hz. The pulse you notice is the difference between them, formed in your hearing rather than in the room.
Are Schumann resonances real?
Yes. They are measured electromagnetic oscillations in the cavity between the Earth and the ionosphere. The unsupported part is what listening to a tone named after them is said to do.
Does it work on speakers?
You will hear the hum, but not the pulse as intended. Both ears receive both tones over speakers, so the beat largely disappears.