Gamma waves (roughly 30–100 Hz) are the fastest rhythm commonly measured in the brain. They show up when the brain binds information together, for example while forming a memory or noticing a pattern. A 40 Hz binaural beat is made by playing two tones 40 Hz apart, one in each ear.
Interest in 40 Hz rose sharply after MIT studies in mice, and many people now search for "40 Hz sound" hoping to support memory. Here is what the research on 40 Hz binaural beats in people actually shows.
What the research on 40 Hz binaural beats shows
Two meta-analyses found a medium overall effect of binaural beats on memory and attention 1 2. Those results pool many frequencies, though, so they do not show that 40 Hz specifically is best.
Studies that tested gamma beats directly are encouraging but mixed. Gamma beats made people more cognitively flexible when switching between two tasks 3 and removed the "attentional blink," but only for some participants 4. In a 2025 study, gamma beats improved general attention without stopping attention from fading over a long task 5.
Other studies found no benefit. In a sentence-comprehension study, 40 Hz did not help where 18 Hz did 6, and in a fatigue study accuracy at 40 Hz dropped mid-task while it held steady at 15 Hz 7.
What about 40 Hz and Alzheimer’s?
The well-known 40 Hz Alzheimer’s research used flickering light and sound pulses in mice, not binaural beats 8 9. Those findings do not carry over automatically to binaural beats or to people. Neuro Gardens is a wellness app, not a treatment for any disease.
Who might try 40 Hz
People who want to try a gamma session before studying, reviewing notes or doing creative problem-solving. Results in the research varied from person to person, so it is worth comparing 40 Hz with 15 or 18 Hz to see which suits you.
How to listen
- Use headphones for binaural beats. Each ear needs its own tone. Isochronic tones work on speakers.
- Start before the task. A meta-analysis found that listening before (or before and during) a task worked better than listening only during it, and that longer sessions helped.
- Keep the volume low. The beat works at a comfortable, quiet level. Louder is not better.
- One goal at a time. Studies tested one beat frequency at a time. You can layer sounds in Neuro Gardens, but there is no evidence that stacked frequencies add up.
About the evidence
Binaural-beat research is promising but uneven. Studies are often small and use different settings, and a 2023 systematic review found that only 5 of 14 EEG studies showed the brain following the beat frequency (Ingendoh 2023). We rate each frequency honestly, link every study to PubMed, and update these pages as new research is published.
Frequently asked questions
What do 40 Hz binaural beats do?
They play two tones 40 Hz apart, one in each ear, so the brain perceives a 40 Hz beat in the gamma range. Studies have linked gamma beats to changes in cognitive flexibility and attention, but results are mixed and vary between people.
Are 40 Hz binaural beats good for memory?
Meta-analyses find a medium overall effect of binaural beats on memory and attention, but they pool many frequencies. Direct evidence for 40 Hz specifically is mixed.
Is 40 Hz sound a treatment for Alzheimer’s?
No. The 40 Hz Alzheimer’s research was mostly done in mice with flickering light and sound pulses, not binaural beats. Talk to a doctor about any memory concern.
Studies cited
All studies link to PubMed, run by the National Library of Medicine at the U.S. National Institutes of Health (NIH).
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Basu S, Banerjee B · Psychological Research · PMID 35842538
Across 15 studies and 31 effect sizes, binaural beats had a medium overall effect on memory and attention (g = 0.40). The authors note conflicting results between frequencies and call for better-designed studies.
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Efficacy of binaural auditory beats in cognition, anxiety, and pain perception: a meta-analysis
Garcia-Argibay M, Santed MA, Reales JM · Psychological Research · PMID 30073406
Across 22 studies, binaural beats had a medium overall effect (g = 0.45) on memory, attention, anxiety and pain. Listening before a task worked better than listening only during it, longer exposure helped, and masking noise was not required.
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High-frequency binaural beats increase cognitive flexibility: evidence from dual-task crosstalk
Hommel B, Sellaro R, Fischer R, Borg S, Colzato LS · Frontiers in Psychology · PMID 27605922
Gamma-range binaural beats increased crosstalk between two tasks compared with a steady 340 Hz tone, which the authors read as a shift toward a more flexible cognitive-control style.
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Eliminating the attentional blink through binaural beats: a case for tailored cognitive enhancement
Reedijk SA, Bolders A, Colzato LS, Hommel B · Frontiers in Psychiatry · PMID 26089802
High-frequency binaural beats eliminated the attentional blink, but only in people with low spontaneous eye-blink rates. The effect depended on the individual.
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A parametric investigation of binaural beats for brain entrainment and enhancing sustained attention
Melnichuk A, Cooper RK Jr, Hawk LW Jr · Scientific Reports · PMID 39910150
Gamma beats with a low carrier tone and white-noise background improved general attention but did not reduce the decline in vigilance over time. EEG confirmed entrainment, which varied with the beat settings.
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Neural consequences of binaural beat stimulation on auditory sentence comprehension: an EEG study
Kim J, Kim HW, Kovar J, Lee YS · Cerebral Cortex · PMID 38044462
After 10 minutes of listening, the 18 Hz group showed more beta-band EEG power and was more accurate and faster at understanding complex spoken sentences than the pure-tone group. The 40 Hz group did not show these effects.
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Wang X, Lu H, He Y, Sun K, Feng T, Zhu X · Brain Sciences · PMID 36138896
During a fatiguing task, accuracy held steady in the 15 Hz group but dropped mid-task in the 40 Hz and relaxing-music groups. EEG suggested more efficient brain networks after 15 Hz. Questionnaire and vigilance scores did not differ between groups.
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Gamma frequency entrainment attenuates amyloid load and modifies microglia
Iaccarino HF, Singer AC, Martorell AJ, et al. · Nature · PMID 27929004
In mouse models of Alzheimer’s disease, 40 Hz flickering light reduced amyloid in the visual cortex. This used light, not binaural beats, and was done in mice.
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Multi-sensory gamma stimulation ameliorates Alzheimer’s-associated pathology and improves cognition
Martorell AJ, Paulson AL, Suk HJ, et al. · Cell · PMID 30879788
In mice, 40 Hz sound pulses (not binaural beats), alone or combined with light, reduced Alzheimer’s-related pathology and improved memory tasks.
Try 40 Hz in Neuro Gardens
Pick Memory Boost on the outcome wheel, choose music from ambient, jazz, lo-fi, classical or nature, and press play. Audio keeps going with your screen locked.
Get notified at launchNeuro Gardens is a general wellness app, not a medical device, and is not intended to diagnose, treat, cure or prevent any disease. Studies cited here are research on binaural beats in general, not tests of Neuro Gardens. Never listen to low frequencies while driving.