Understanding binaural beats

A discovery from 1839

In 1839, the Prussian physicist Heinrich Wilhelm Dove noticed a curious effect. When two tones of slightly different frequencies are played, one to each ear, you perceive a regular pulse that exists in neither tone. The phenomenon was popularised much later, in 1973, by the biophysicist Gerald Oster.^[1]

How it works

Play 460 Hz in the left ear and 464 Hz in the right ear. Each ear only hears a pure, steady tone. Yet you perceive a gentle pulse, four times per second: 464 − 460 = 4 Hz.

The beat is produced by the nervous system. The signals from both ears meet in the brainstem, in the superior olivary complex, which compares their timing. That comparison is what creates the pulse.^[1]

Fig. 1 — The left ear receives 460 Hz, the right ear 464 Hz. The brain perceives a pulse at the difference: 4 Hz, four beats per second. Diagram: frequencies slowed down for legibility.

The beat is clearest when both tones are low or mid-pitched, around a few hundred hertz, and the gap between them stays small. Once the gap exceeds about thirty hertz, the pulse becomes hard to perceive as such.

The five bands

The brain's electrical activity, measured by electroencephalography (EEG), is grouped into frequency bands. Each is associated with the states in which it is most often observed.

Delta 0.5 – 4 Hz Associated with deep sleep
Theta 4 – 8 Hz Daydreaming, meditation
Alpha 8 – 13 Hz Relaxed wakefulness
Beta 13 – 30 Hz Attention, focus
Gamma 30 – 100 Hz Intense information processing

Fig. 2 — The five bands on a logarithmic scale, from 0.5 to 100 Hz. The associations describe the states in which these rhythms are most often observed, not guaranteed effects.

The idea behind binaural beats is called entrainment: a 6 Hz beat would encourage the brain to produce more 6 Hz activity, in the theta band. It is a hypothesis, and that is exactly what research is trying to test.

What the research says

The results are encouraging on some points and mixed on others. We'd rather tell you plainly.

A 2019 meta-analysis pooling 22 studies found a moderate effect of binaural beats on anxiety, on some memory and attention tasks, and on pain perception. Listening time influences the effect.^[2]

The brain-entrainment hypothesis is less solid. A 2023 systematic review examined 14 studies that measured brain activity directly with EEG: five support entrainment, eight contradict it, and one gives mixed results. The authors mainly point to the lack of comparable protocols between studies.^[3]

Some studies do observe measurable effects. In 2017, one team reported a change in theta activity in participants exposed to a 6 Hz beat.^[4]

Before you listen

Headphones or earphones are essential. On speakers, the binaural effect disappears.
Keep the volume moderate. The beat is easy to perceive at low volume.
Never while driving or operating machinery: some bands encourage drowsiness.
Epilepsy, heart condition, pregnancy: ask a doctor before using the app.
This is not a treatment. NeuroHarmonics does not replace any medical advice or care.

References

Oster, G. (1973). "Auditory beats in the brain". Scientific American, 229(4), 94–102.
Garcia-Argibay, M., Santed, M. A. & Reales, J. M. (2019). "Efficacy of binaural auditory beats in cognition, anxiety, and pain perception: a meta-analysis". Psychological Research, 83(2), 357–372. doi.org/10.1007/s00426-018-1066-8
Ingendoh, R. M., Posny, E. S. & Heine, A. (2023). "Binaural beats to entrain the brain? A systematic review of the effects of binaural beat stimulation on brain oscillatory activity". PLOS ONE, 18(5). doi.org/10.1371/journal.pone.0286023
Jirakittayakorn, N. & Wongsawat, Y. (2017). "Brain responses to a 6-Hz binaural beat: effects on general theta rhythm and frontal midline theta activity". Frontiers in Neuroscience, 11, 365. frontiersin.org

Further reading: "The science behind binaural beats", a popular-science article written by Lake Forest College students (Eukaryon, 2025).