440 Hz and 432 Hz are two choices for the same note: the A above middle C (A4), which instruments use as the reference when they tune. In standard tuning A4 vibrates 440 times a second; in "432 Hz tuning" it vibrates 432 times, and every other note moves down by the same proportion. The difference is 31.77 cents, about a third of a semitone: audible when you compare the two side by side, too small for most people to notice in a song on its own.
How big the difference really is
Pitch is heard as a ratio, not a difference in hertz. Musicians measure it in cents: an octave is 1,200 cents and a semitone (the step between two neighbouring piano keys) is 100 cents. A semitone is a frequency ratio of 21/12, about 1.0595.
From 440 to 432 Hz is a ratio of 0.9818, which is 1200 × log2(432/440) = −31.77 cents. In practice:
- It is less than half the gap between two piano keys, so a 432 Hz recording does not change key. A song in C major is still in C major, just slightly flat.
- Played one after the other, most listeners can hear that one is lower. Played alone, few people can tell which tuning a recording uses; people with absolute pitch notice it sounds "between keys".
- The tempo doesn't change when a song is retuned properly; only the pitch moves.
To hear it yourself, play 440 Hz and then 432 Hz on the tone generator, ideally as sine waves at a low volume.
How 440 Hz became the standard
For most of musical history there was no standard at all. Organs, orchestras and cities each had their own pitch, ranging from below A = 400 Hz to above 460 Hz. Baroque ensembles today often tune to A = 415 Hz to imitate the lower pitch common in the 18th century.
- 1859: France set the diapason normal at A = 435 Hz to stop the "pitch inflation" that strained singers' voices as orchestras tuned ever higher.
- 1884: Giuseppe Verdi argued in a letter for a standard of A = 432 Hz in Italy. This is the historical root of most 432 Hz claims, though his argument was about consistency and singers, not about health.
- 1939: an international conference in London recommended A = 440 Hz, already the norm in much of the American music industry.
- 1955 and 1975: the International Organization for Standardization adopted 440 Hz as ISO 16.
Even today 440 Hz is a reference, not a law. Many European orchestras tune to 442 or 443 Hz for a brighter sound, and some bands tune lower for a darker one.
What the 432 Hz movement claims
Supporters say 432 Hz is "mathematically consistent with the universe", resonates with the body or the Earth, and sounds warmer and more relaxing. Some add that 440 Hz was imposed to make music more agitating.
The physics doesn't support the first part. The hertz is defined by the second, a human unit; a number that looks special in hertz would look ordinary in any other unit of time. The Earth's "Schumann resonance" is about 7.8 Hz and unrelated to 432. And there is no historical evidence for the conspiracy stories about 440 Hz: it came out of a standards meeting that picked the pitch much of the industry already used.
The "warmer" part is more plausible and much simpler: lower pitch makes instruments and voices sound slightly darker, and a recording tuned down without care can lose some brightness.
What the studies found
Only a handful of controlled studies exist, all small:
- Calamassi and Pomponi, 2019 (Explore journal): 33 volunteers listened to the same film soundtracks at 440 Hz and at 432 Hz, double-blind. With 432 Hz, average heart rate was 4.79 beats per minute lower (p = 0.05) and breathing slightly slower; blood pressure differences were not significant. The authors called it a pilot study and asked for larger trials.
- Aravena et al., 2020: dental patients who heard music at either tuning were far less anxious than those in silence, with almost identical anxiety scores between the two tunings; cortisol was lower in the 432 Hz group.
- Jebabli et al., 2025: kickboxers warming up to music performed better with 440 Hz than with 432 Hz.
The fair summary: music relaxes people at either tuning, and the extra effect of 432 Hz, if there is one, is small and not yet shown in a large trial. If 432 Hz sounds better to you, that is a perfectly good reason to use it; it just isn't a medical one.
What about 528 Hz and the "Solfeggio frequencies"?
528 Hz is one of six "Solfeggio frequencies" (396, 417, 528, 639, 741 and 852 Hz) popularised in the 1970s and 1990s, with claims such as DNA repair. Those claims have no support in published research. 528 Hz is simply a tone slightly above C5 in standard tuning; you can play it on a tone generator, but it isn't a tuning system and doesn't change the key of a song.
How to listen to or make music in 432 Hz
- Convert a recording: the pitch changer has a 440 → 432 Hz preset that lowers a song by exactly 31.77 cents and keeps its tempo, in the browser.
- Tune an instrument: set the reference of the guitar tuner to A4 = 432 Hz (its calibration goes well below and above 440) and tune as usual.
- Compare blind: have someone play the original and the converted version in random order. If you can't pick the 432 Hz version reliably, the tuning isn't what you like about it.
FAQ
Is 432 Hz better than 440 Hz?
Neither is objectively better. 440 Hz is the convention that lets musicians play together; 432 Hz is a slightly lower alternative some people prefer the sound of.
Can you hear the difference between 432 and 440 Hz?
Side by side, yes: 432 Hz is about a third of a semitone lower. Without a comparison, most people can't tell.
Is 432 Hz the same as tuning down a semitone?
No. A semitone down from A = 440 Hz is A = 415.3 Hz. 432 Hz is less than a third of that step.
Are songs on Spotify in 432 Hz?
Almost all commercial music is recorded at A = 440 Hz or close to it. "432 Hz" versions on streaming services are usually standard recordings pitched down afterwards.