The science · Solfeggio
417 Hz, explained
417 Hz is one of the original six solfeggio values, a set first put forward in the 1970s. Popularly linked with change and fresh starts, it is a description of what people say about it, not of an effect. In Sonor it is a carrier pitch: it changes the note you hear, not the band.
What the research says
The numbers were derived in the 1970s by Joseph Puleo from a pattern of verse numbers in the Bible's Book of Numbers (Science Feedback, 2022). A popular story says medieval monks sang these pitches. There is no evidence for that, and the values do not fit any musical scale in use. A fact-check found no scientific or clinical evidence that any solfeggio frequency regenerates the body or removes toxins.
A PubMed search for 417 Hz combined with music, sound, tone, solfeggio, healing or acoustic returned three records. All three are unrelated to listening to a 417 Hz tone.
No peer-reviewed study was located that tested a 417 Hz tone for any effect on people or animals.
How Sonor uses it
417 Hz is a named carrier pitch for the isochronic tone. Choosing it changes the note you hear. The pulse rate, and so the band, stays the same. Sonor also offers 432 Hz as a separate extra, which is not part of the solfeggio set. See What are carrier frequencies? for what a carrier does.
You can hear Sonor's tones on the listen page.