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741Hz
741 Hz is one steady tone, the same in both ears, with nothing behind it. Of the six solfeggio pitches here it is the only one that lands on a real note — an F sharp, close enough that nobody will hear it as out of tune. It is also high enough to get tiring, so start the volume lower than feels right.
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.
The one that is in tune
Two cents off a note is a gap no listener detects, so this tone will sit inside music tuned to concert pitch without beating against it. That separates it from the 639 Hz tone, which falls between two semitones and clashes with everything. The tone carries no harmonics and nothing else audible alongside it.
Up at this pitch a pure tone is easy to hear at very low levels and turns fatiguing fast when pushed. Set the volume from where you actually plan to sit, then leave it there.
The cleansing claims
This number is marketed for detoxification and for clearing cells of toxins. No systematic review or clinical guideline addresses solfeggio frequencies, and no mechanism has ever been proposed that survives contact with how sound works: a tone moves air, and air at ordinary listening levels does not act on cells. The set was compiled in the 1970s from a numerological reading of the Book of Numbers.
The lower pitches are on the 396 Hz tone and the 285 Hz tone. Everything on the site is listed on the sound library index, or open the 741 Hz and brown noise blend in the free sound mixer to give the pitch some weight underneath.
Frequently asked questions
What note is 741 Hz?
F sharp 5, near enough. It sits two cents away from the note, which nobody will hear as out of tune.
Does 741 Hz detoxify cells?
No. Nothing supports that claim, and no plausible mechanism has been offered. Sound at listening levels moves air; it does not act on cells.
How loud should I play it?
Quietly. A pure tone at this pitch is audible at low volume and becomes tiring fast when turned up.
Will it mask background noise?
Not usefully. All of its energy sits at one pitch, so a broadband sound such as brown or pink noise covers a room far better.