The science · Solfeggio
741 Hz, explained
741 Hz is one of the original six solfeggio values, a set first put forward in the 1970s. Popularly linked with clarity and self-expression, 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.
741 Hz is the value a fact-checker examined directly. Science Feedback reviewed a widely shared 2022 video claiming a 741 Hz tone could aid body regeneration and remove toxins. It found no scientific or clinical evidence for that, or for any effect of solfeggio frequencies on mental health or behaviour. It added that the body removes toxins through the liver and kidneys, and that no mechanism exists for an audible tone to affect that process.
A PubMed search for 741 Hz combined with music, sound, tone, solfeggio, healing or acoustic returned no records.
No peer-reviewed study was located that tested a 741 Hz tone for any effect.
How Sonor uses it
741 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. See What are carrier frequencies? for what a carrier does.
You can hear Sonor's tones on the listen page.