Binaural beats correspond to a sound illusion effect that occurs when two tones at close frequencies are emitted to the left and right ears (eg via headphones or speakers), giving the sensation of a beat.
In 1839 a Prussian physicist, Heinrich Wilhelm Dove, realized that this phenomenon occurs when the following conditions are met :
- Sine waveform.
- Left / right frequencies lower than 1000 Hertz (Hz).
- Difference of 40 Hertz or less between the two frequencies.
For instance, the following values produce a binaural beat :
- Left ear : 261.915 Hz.
- Right ear : 254.085 Hz.
Audio sample with above values :
Source : freesound.org
Binaural beats induce particular effects on the brain via brain waves (electrical activity acting on brain cells), according to the frequency ranges.
Specifically, the main types of brain waves are the following ones :
- Beta waves (14 Hz – 40Hz) : Awareness, alertness.
- Alpha waves (7.5 Hz – 14Hz) : State of deep relaxation / light meditation / light sleep.
- Theta waves (4 Hz – 7.5Hz) : Meditative, slumbery states / light sleep / hypnosis.
- Delta waves (0.5 Hz – 4Hz) : Deep states of unconsciousness / sleeping.
- Infra-low (< 0.5 Hz) : Low frequency rhythmic activity whose role is not yet well known. Seems to play an important role in brain timing and network function.
- Gamma waves (above 40 Hz) : Most recently discovered range, it goes with a high level of brain activity and concentration peaks.
Binaural beats can be useful for many purposes, among which :
- Calibrating / testing sound equipment or loudspeakers.
- Acoustic testing, equalization.
- Hearing tests.
- Binaural beats therapy.
- Creation and use of audio samples.
Want to create your own binaural beats ? Check out our Audio Frequency Signal Generator mobile app, a free utility for generating and recording binaural frequencies. Enjoy !
Also check out our Frequency List, a page that describes some interesting frequencies that you can test with the app.