The science · Brain waves
Gamma, explained
Gamma is the fastest of the five bands. The best-known auditory finding in it is the 40 Hz response: sound pulsed about 40 times a second produces a steady brain signal that researchers can record from the scalp. Here is what that does and does not show, and what Sonor does with the band.
What the research says
The clinical EEG glossary defines gamma as above 30 Hz up to 80 Hz (Kane et al. 2017). Sonor's gamma range stops at 50 Hz.
The 40 Hz response was first described in 1981 (Galambos et al. 1981). A 2003 review describes steady-state responses for rates from 1 to 200 Hz, particularly prominent near 40 Hz in waking listeners and used in hearing assessment (Picton et al. 2003). This is a measurement of the brain following the sound. It does not by itself show any change in how you think or feel.
Intracranial recordings in presurgical epilepsy patients found the most prominent power increases after monaural 40 Hz beats, where the beat is physically in the sound, as with isochronic tones (Becher et al. 2015). A 2023 review of 14 EEG studies found two that reported gamma power increases during gamma-range binaural beats and one that reported none (Ingendoh et al. 2023).
In a 2021 study, 25 students did an attention task during pink noise, 40 Hz monaural beats and 40 Hz binaural beats. Errors were fewer with binaural beats and more with monaural beats than with pink noise, and the EEG did not show the expected 40 Hz increase (Engelbregt et al. 2021).
Overall, the evidence for a brain response at 40 Hz is strong. The evidence for any listener outcome in healthy adults is weak. We make no claim about what gamma tones do for you. Research on 40 Hz stimulation in Alzheimer's disease used different methods, usually light plus sound, in patients, and does not apply here.
How Sonor uses it
Sonor's gamma range pulses the tone from 30 to 50 times a second. The picker offers 30, 40 and 50 Hz. The pulse plays continuously, quietly under music or ambient sound. It is not timed to your own brain waves.
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.