Beatline
The research
Binaural beats vs solfeggio frequencies
16 August 2026
These two get shelved together and they are not the same kind of claim at all.
A binaural beat is about the difference between two frequencies. A solfeggio frequency is about one absolute pitch: 528 Hz, or 432 Hz, or one of the other numbers in the set, played as itself.
That distinction matters because it changes what would have to be true for each to work.
What the solfeggio claim requires
For a binaural beat to do something, your auditory system has to construct a pulse and that pulse has to influence something downstream. Contested, but coherent.
For a solfeggio frequency to do something, a specific pitch has to have a specific effect that neighbouring pitches do not. 528 Hz would need to do something 527 Hz does not.
That is a much stronger claim, and the numbers themselves have a weaker pedigree than their presentation suggests. The set is usually attributed to a mediaeval hymn, which is a historical association rather than an acoustic finding. Nobody measured anything to arrive at 528.
What the research actually found
Here the picture is more interesting than "it is nonsense", which is why we carry these tones in the app and grade them the way we do.
Calamassi and Pomponi 2019 ran a double-blind crossover pilot and found a small heart-rate difference for 528 Hz. A real result, in a real design, and the authors themselves asked for larger trials.
Then Calamassi 2022 ran the larger thing: 54 nurses, three arms. Anxiety fell in every arm, including the one with no music at all, and there was no significant difference between them.
That second study is the one to sit with. It does not say the participants felt nothing. It says they felt better regardless of what they listened to, which means the tuning was not what did it.
What probably is doing it
de Witte 2020 pooled 104 randomised controlled trials with 9,617 participants and found music reduces stress. That is a far larger evidence base than anything in the solfeggio literature, and it explains the effect without reference to tuning at all.
Music helps. A sustained pure tone at a comfortable volume is a mild, structureless sound, and mild structureless sound helps people settle. Neither explanation needs 528 to be special.
How that compares with binaural beats
Binaural beats are on firmer ground, though not dramatically so.
Garcia-Argibay, Santed and Reales 2019 pooled 22 studies for g = 0.45, medium-sized. Baseanu 2024 found binaural beats beat silence and beat noise-cancelling headphones, which is the comparison that starts ruling out "any quiet is good quiet".
Solfeggio has no equivalent. Its best result is a pilot the authors flagged as preliminary, followed by a larger study that found no difference between arms.
The gap is real, but keep it in proportion: both effects are modest, and the binaural mechanism is itself contested. Ingendoh 2023 found 8 of 14 studies contradicted entrainment. Neither of these is a treatment.
Why 432 Hz and 528 Hz are still in the app
Because people like them, and we would rather offer a tone somebody enjoys with an honest label than withhold it or dress it up.
The app grades solfeggio "not the tuning", which is the shortest true summary we could write. The tone is real, the tuning is not doing what the internet says it does, and if a 528 Hz drone settles you then it settles you.
What we will not do is print the frequency-and-organ charts. Nobody measured those.