432 Hz against 440 Hz

One is the international standard, the other has a following. Here is the history, the claims and what holds up.

What the numbers mean

Both are tunings for the note A above middle C, the reference every other note is derived from. At 440 Hz, that A vibrates 440 times a second; at 432 Hz, 432 times. The difference is about 32 cents, roughly a third of a semitone — clearly audible when you switch between them directly, and easy to miss when you do not.

You can hear it now. Open the tone generator and press the 440 Hz preset, then the 432 Hz one. The readout will tell you the second is A4 about 32 cents flat, which is the honest description: the same note, slightly lower, not a different note.

How 440 became the standard

For most of musical history there was no standard at all. Surviving instruments and tuning forks from the eighteenth and nineteenth centuries sit anywhere from roughly A=400 Hz to A=460 Hz, varying by city, by decade and by whether the music was for a church organ or an opera house. Pitch drifted upward over time, partly because a brighter, more brilliant sound was fashionable and partly through competition between orchestras.

That variation became impractical as recording, broadcasting and international touring grew. A 1939 international conference settled on A=440 Hz, and it was adopted as an ISO standard in 1955. It is a convention chosen for coordination, not a claim that 440 is acoustically special.

Where 432 comes from

The 432 figure is usually traced to Giuseppe Verdi, who argued for a lower pitch to suit singers and supported a proposed Italian standard of A=432 Hz. That much is historical. The rest of the modern case for it is not: claims that 432 Hz is the "frequency of the universe", that it matches the Earth's resonance, or that it aligns with a particular mathematical constant are numerology rather than physics.

The Schumann resonance often cited is about 7.83 Hz, an electromagnetic phenomenon in the cavity between the Earth's surface and the ionosphere. It is not a sound, and the arithmetic connecting it to 432 Hz requires several arbitrary choices of multiplier.

What research shows

A handful of small studies report differences in relaxation or heart rate when listening to music at the two tunings. They involve few participants, generally lack proper blinding, and have not been replicated at scale. Larger and better-controlled listening tests have not found a reliable preference.

There is also a straightforward confound in the popular demonstrations. Most "432 Hz versions" on the internet are ordinary recordings slowed down, which lowers the pitch and the tempo together and also alters timbre. A slower, slightly darker recording may well feel calmer, and none of that is evidence about the tuning itself.

Reasons a musician might still choose it

Singers sometimes prefer a slightly lower pitch because it moves a demanding passage away from the top of their range. Ensembles playing early music often tune lower still, around A=415 Hz, because gut strings at modern tension sound and behave differently from what the music was written for. Those are practical reasons, and they are enough on their own.

The trade-off is coordination. Tuning to 432 means every instrument in the room has to follow, including any with fixed pitch, and any recording you play along with. That is why the standard exists at all.

Trying both

The generator will sit on either number for as long as you like, and it will also hand you a WAV of each so you can use them as a reference away from the browser. Use the arrow keys to walk between 432 and 440 one hertz at a time, and listen for the beating against an instrument — it slows as you approach a match and stops when you land on it. That beating is also the most practical tuning tool on this page.

Last reviewed 2026-09-22.