40 Hz frequency: gamma sound
40 Hz is in the gamma band of brain activity. It became famous through MIT research on flickering light and clicking sound at 40 pulses per second in mice models of Alzheimer’s disease.
- Nearest noteD#1 +49¢
- Period25.0 ms
- Wavelength in air8.57 m
To mirror the research format more closely, use the isochronic mode with a 40 Hz pulse rate, rather than a plain 40 Hz sine (which is a barely audible rumble on most speakers).
What 40 Hz is claimed to do
- Promoted for memory, focus and “brain cleaning”
- Sold as a sleep and cognition aid
- Often offered as a 40 Hz binaural beat
What the evidence says
Li-Huei Tsai’s lab reported in Nature (2016) and Cell (2019) that 40 Hz light and sound stimulation reduced amyloid markers in mice. Small human trials of 40 Hz sensory stimulation are ongoing; results so far are early. Importantly, those studies use 40 Hz clicks or pulses (like isochronic tones), not a steady 40 Hz hum, and not binaural beats. This page is not a treatment.
40 Hz: common questions
What is 40 Hz sound therapy?
Exposure to sound pulsing 40 times per second, studied as a way to encourage gamma-band brain activity. It is experimental.
Does 40 Hz help Alzheimer’s?
Mouse studies were promising and small human trials are under way, but it is not an approved treatment. Talk to a doctor about any memory concerns.
Is a 40 Hz binaural beat the same thing?
No. The research used audible clicks at 40 Hz. A 40 Hz binaural beat is perceived far less strongly, since beats above about 30 Hz fade.