285 Hz, 528 Hz and 852 Hz: three Solfeggio tones played together

What are 285 Hz, 528 Hz and 852 Hz?

They are three of the nine tones in the modern Solfeggio set, and each has its own Harmonance page: 285 Hz, the restoration theme, 528 Hz, love and renewal, and 852 Hz, inner listening. Each plays alone on its page, and the Solfeggio collection plays all nine.

Two of the three are older than the third. 528 and 852 are among the six numbers printed in 1999 in Healing Codes for the Biological Apocalypse, by Leonard Horowitz and Joseph Puleo. The publisher's press release said the numbers were found in the Book of Numbers, chapter 7, by "reducing the verse numbers to their single digit integers", and called them "the six missing tones of the ancient Solfeggio scale".

285 came later. In an essay in the journal Prabuddha Bharata, Horowitz lists the six as "396, 417, 528, 639, 741, and 852" and says that from them he "conceived of ‘The Perfect Circle of Sound’", a set of nine. All nine appear together in a US trademark application filed in February 2007 under that name, which lists them as "396, 417, 528, 639, 741, 852, 963, 174, and 285". 285 comes last.

The 285 Hz guide, the 528 Hz guide and the 852 Hz guide follow each number on its own. This guide is about the three together.

Why are 285, 528 and 852 grouped together?

They share their digits. Write the nine Solfeggio numbers in three rows of three, lowest first, and 285, 528 and 852 form the middle column: the digits 2, 5 and 8, turned. Each adds up to 15, and 1 and 5 add up to 6. The first column, 174, 417 and 741, works the same way, and the guide to 174, 417 and 741 Hz draws the whole grid.

That pattern lives in the digits, not in the sound. In pitch the three are not evenly spaced: 528 Hz sits 243 Hz above 285 Hz, and 852 Hz sits 324 Hz above 528 Hz. Harmonance found no early Solfeggio text that names these three as a set, and the 1999 book had no 285 at all.

How do 285 Hz, 528 Hz and 852 Hz sound together?

They sound smooth rather than rough, because they sit far apart in the ear. In a classic study, Plomp and Levelt found that listeners judged two plain tones consonant once they were more than one critical band apart, the stretch of the inner ear that a single tone sets moving, and least consonant at about a quarter of a band.

By Glasberg and Moore's formula, 24.7 × (0.00437 f + 1), which hearing scientists use today, the band is about 69 Hz wide halfway between 285 and 528 Hz, and about 99 Hz wide halfway between 528 and 852 Hz. So 285 and 528 Hz sit 3.5 bands apart, and 528 and 852 Hz 3.3 bands apart: well past the point where roughness fades out.

The three pairs

Pair	How far apart	The interval
285 and 528 Hz	243 Hz, 3.5 bands	1,067.5 cents, between a minor and a major seventh
528 and 852 Hz	324 Hz, 3.3 bands	828.4 cents, a little over a minor sixth
285 and 852 Hz	567 Hz, 6.6 bands	1,895.9 cents, 6.1 cents short of an octave and a fifth

None of the three pairs is a familiar musical interval, with one near miss. 852 Hz sits 1,895.9 cents above 285 Hz, a hair short of an octave and a fifth, 1,902 cents, the distance from any tone to three times its pitch.

Why does 852 Hz almost match 285 Hz?

Because 852 is almost exactly three times 285. Three times 285 is 855, so 852 Hz falls 3 Hz short of it: 6.1 cents, about a sixteenth of a semitone.

That matters because most sounds hold more than one frequency. A plucked string vibrates at its pitch and also at two, three and more times it, its harmonics, and an instrument's colour is the mix. A perfectly pure tone has none. Harmonance's tone files sit close to pure: each holds its pitch and two faint harmonics, the second 23 dB below it and the third 34 dB below. So the 285 Hz page plays a faint line at 855 Hz, and 852 Hz lands right beside it.

Two tones that close beat. Their waves drift in and out of step, so the sound swells and fades, and as the physics notes from UNSW Sydney put it, "The beat frequency equals the difference between frequencies of the beating signals." For 852 and 855 Hz that is 3 beats a second, slow enough to count. Guitarists tune by beats of exactly this kind: the same notes show the third harmonic of one string beating against another string, and the beats slowing as the string is brought into tune.

How strong is the beat in Harmonance's tones?

It is there, and it is very faint. Harmonance played its three tone files together, sample for sample, and measured the sound between 838 and 869 Hz on its own. Its level rises and falls exactly 3 times a second, by 0.35 dB from top to bottom, about 2 per cent: the harmonic is 34 dB below the 852 Hz tone, so it can only nudge it. That 3 Hz swing accounts for 98 per cent of the movement left once the files' slow 20 second swell is set aside.

Harmonance has measured the beat, not tested whether people notice it, and a swing that small may pass many listeners by. With perfectly pure tones there would be no line at 855 Hz, and nothing for 852 Hz to beat against.

One more pair sits close. 285 Hz's second harmonic, 570 Hz, lies 42 Hz above 528 Hz, about half a critical band. In Plomp and Levelt's terms that is the rough side of the scale, but 42 a second is too fast to hear as beating, which the UNSW notes say stops at "roughly 20 or 30 times per second", and the line is 23 dB below the tone.

What is in Harmonance's 285 Hz, 528 Hz and 852 Hz tones?

Each page plays a 20 second loop. Played together and measured, the three strongest lines sit at 285.000, 528.000 and 852.000 Hz, at the same level. Above each sit its second harmonic, 23 dB down, and its third, 34 dB down, and nothing else in the files comes within 54.4 dB of the tones.

The numbers behind the chart

Line	What it is	Below the tones
285 Hz	the 285 Hz tone	0 dB
528 Hz	the 528 Hz tone	0 dB
570 Hz	second harmonic of 285 Hz	23.0 dB
852 Hz	the 852 Hz tone	0 dB
855 Hz	third harmonic of 285 Hz	34.0 dB
1,056 Hz	second harmonic of 528 Hz	23.1 dB
1,584 Hz	third harmonic of 528 Hz	34.0 dB
1,704 Hz	second harmonic of 852 Hz	23.1 dB
2,556 Hz	third harmonic of 852 Hz	34.0 dB

Download the measurements (CSV)

So the pages play three near-pure tones at one level, and only two of their faint harmonics land near another tone: 570 Hz near 528 Hz, and 855 Hz beside 852 Hz. Each tone also plays with Strings on its own page, where strings tuned to the tone carry the music and the exact tone sits underneath.

What do studies show about 285 Hz, 528 Hz and 852 Hz?

No study has played 285, 528 and 852 Hz together. Two small studies played at least two of them to people, and both played their tones in rising order every time.

In Canberra, 37 adults heard twelve pure tones, the nine Solfeggio tones among them, for 20 seconds each, and rated how happy, sad, calm and angry each one sounded on a scale of 1 to 10 (Kumar, Abhayapala and Samarasinghe, 2022). Across these three, calm fell and anger rose with pitch.

Ratings out of 10

Tone	Calm	Angry
285 Hz	6.7	3.1
528 Hz	3.3	6.2
852 Hz	2.2	8.5

The test asked how each tone sounded, not how anyone felt, and the paper says each tone was rated by "comparative analysis of the previous and next tone, as they are in ascending order of frequency". So the steady slide may follow the order as much as the pitch. The volunteers listened on their own headphones at home, and the sample was young, with an average age of 27.

At a university in the United States, 18 adults heard six pure Solfeggio tones, 528 and 852 Hz among them, and then all six at once, always in rising order, five minutes each, at 75 to 79 decibels (Presley, Stamps and Davis Alexander, 2026). Skin conductance, a sign of arousal, rose significantly for 741 Hz, 852 Hz and the six combined, and not for 528 Hz. Afterwards, five of the 18 said they felt annoyed, tired and less calm. The authors plan to randomise the order next, to separate "sequential increases versus exposure". 285 Hz was not played.

A 2026 review that is hopeful about such tones still says of 852 Hz and two others that "there is currently little direct empirical evidence supporting these individual frequencies" (Whitney and colleagues, 2026). Research on music as a whole is at an early stage too. The US National Center for Complementary and Integrative Health sums it up:

However, because much of the research on music-based interventions is preliminary, few definite conclusions about their effects have been reached.

What is certain is plainer. The three tones sit far enough apart to sound smooth together, and in Harmonance's files one faint harmonic of 285 Hz meets 852 Hz 3 Hz away. Anything more than that, nobody has shown.

How do you play 285 Hz, 528 Hz and 852 Hz together?

Press play at the top of this guide to hear 285 Hz, or open the 285 Hz page, the 528 Hz page and the 852 Hz page. Each plays its tone alone, or with Strings switched on. Nothing plays until you press play, and no account is needed.

To hear all three at once, open Harmonance Studio, the free Harmonance instrument, which plays several tones at once after you sign in with a free account: add 285, 528 and 852 Hz, then balance them by ear. Keep the volume low. Loud listening is the one risk that is well established, and the NCCIH notes that "listening to music at too high a volume can contribute to noise-induced hearing loss".

The Need to unwind page sets 285 Hz beside other tones people reach for at the end of a day, and the Reflective page gathers 852 Hz with others. For another pair heard together, the 528 Hz and 432 Hz guide works through their arithmetic, and what the science of sound healing shows sets out what research on sound has and has not found.

Sources and limits

The history of the three numbers rests on the 1999 book's record and its press release, Horowitz's own essay and a US trademark record. The sound rests on arithmetic anyone can redo, classic papers on hearing and Harmonance's own measurements of the three files the pages play. The research is thin: one online rating test and one small skin conductance study, both in fixed rising order, and no study of the three tones together.

1. Horowitz and Puleo (1999), Healing Codes for the Biological Apocalypse, its Google Books record: the book that printed the first six numbers.
2. Tetrahedron Publishing (1999), the book's press release, Internet Archive copy: six numbers from the Book of Numbers.
3. Horowitz (2015), The Love/528 Revolution, in Prabuddha Bharata: the six numbers, and the nine that followed.
4. US Patent and Trademark Office, application 77099679: all nine numbers, filed in February 2007, 285 last.
5. Plomp and Levelt (1965), tonal consonance and critical bandwidth, in The Journal of the Acoustical Society of America: when two tones sound smooth or rough.
6. Moore (2014), the Cambridge loudness models, in Trends in Hearing: the width of the ear's filters.
7. UNSW Sydney School of Physics, interference beats and Tartini tones: how two close tones beat, and how guitarists tune by it.
8. Kumar, Abhayapala and Samarasinghe (2022), frequency cues for human emotions, in Acoustics: 37 adults rating twelve pure tones.
9. Presley, Stamps and Davis Alexander (2026), Solfeggio tones and skin conductivity, in the Journal of Scientific Exploration: six tones and their combination, 285 Hz not among them.
10. Whitney and colleagues (2026), a review of music, sound frequencies and binaural beats after brain injury and stroke, in Cureus: little direct evidence for 852 Hz.
11. National Center for Complementary and Integrative Health, music and health: the state of the research, and loud listening.