Solfeggio tones, explained

Solfeggio tones are nine fixed pitches, a set first put forward in the 1970s (source 1). In Sonor they are carrier pitches: they change the note you hear, not the band.

• 174 Hz. Lowest of the set. Popularly linked with grounding.
• 285 Hz. Popularly linked with rest.
• 396 Hz. Popularly linked with letting go of fear and guilt.
• 417 Hz. Popularly linked with change and fresh starts.
• 528 Hz. The best known of the set, often called the love tone.
• 639 Hz. Popularly linked with connection and relationships.
• 741 Hz. Popularly linked with clarity and self-expression.
• 852 Hz. Popularly linked with intuition and inner calm.
• 963 Hz. Highest of the set. Popularly linked with a sense of oneness.

These associations are popular lore from the 1970s, not clinical evidence.

Where they come from

The set was put forward in the 1970s by Joseph Puleo, who said he derived the numbers from a pattern he found in verse numbers of the Bible's Book of Numbers. A popular story claims medieval monks sang these exact pitches; there is no evidence behind that story, and nobody can know exactly which pitches were sung centuries ago (source 1). It reached a wide audience through the 1999 book Healing Codes for the Biological Apocalypse (Horowitz and Puleo) (source 3).

What the research says

There is no scientific or clinical evidence that these pitches heal the body or remove toxins (source 1). No peer-reviewed study located tested whether hearing a 528 Hz tone repairs DNA.

One study of nine adults measured stress hormone levels before and after five minutes of piano music retuned so that 528 Hz is in the scale, and after music in standard tuning (source 2). It tested music, not a plain tone, it compared each condition with its own baseline, and it has not been repeated. The authors write that the effects ascribed to the solfeggio frequency have no scientific basis.

432 Hz and 1111 Hz

Sonor also offers 432 Hz and 1111 Hz as carrier choices. Neither is part of the solfeggio set above.

How Sonor uses them

In Sonor, the solfeggio values are carrier pitches, chosen by taste; see What are carrier frequencies? for what a carrier does. Picking one changes how the tone sounds. It never changes the brain wave band, which is set by the beat frequency; see What are isochronic tones? for how that works.

This isn't medical advice. Pulsing audio can affect people with epilepsy or a seizure disorder, so check with a doctor before using it if that applies to you.

Sources

1. Science Feedback. There is no evidence to support claim that Solfeggio frequencies remove toxins from the body. 30 September 2022.
   The set dates from the 1970s, there is no evidence monks sang these pitches, and no scientific or clinical evidence of healing effects.
2. Akimoto K, Hu A, Yamaguchi T, Kobayashi H. Effect of 528 Hz Music on the Endocrine System and Autonomic Nervous System. Health 2018;10(9):1159-1170.
   Nine adults heard five minutes of piano music retuned so that a 528 Hz note is in the scale, and five minutes in standard tuning. This was music, not a 528 Hz tone. Stress hormones moved from baseline after the 528 Hz music and not significantly after the standard music. Not repeated.
3. Horowitz LG, Puleo J. Healing Codes for the Biological Apocalypse. Tetrahedron; 1999.
   The book that spread the set. Only the bibliographic record was read, not the book.