Binaural beats or binaural tones are
auditory processing artifacts, or apparent sounds, the perception
of which arises in the brain independent of physical stimuli.
This effect was discovered in 1839 by Heinrich Wilhelm Dove.
The brain produces a phenomenon resulting in low-frequency
pulsations in the loudness of a perceived sound when two
tones at slightly different frequencies are presented separately,
one to each of a subject's ears, using stereo headphones.
A beating tone will be perceived, as if the two tones mixed
naturally, out of the brain. The frequency of the tones must
be below about 1,000 to 1,500 hertz for the beating to be
heard. The difference between the two frequencies must be
small (below about 30 Hz) for the effect to occur; otherwise
the two tones will be heard separately and no beat will be
perceived.
Interest in binaural beats can be classified into two categories.
First, they are of interest to neurophysiologists investigating
the sense of hearing. Second, that binaural beats may influence
the brain in more subtle ways through the entrainment of
brainwaves and can be used to produce relaxation and other
health benefits.
Brain waves
| Frequency range |
Name |
Usually associated with: |
| > 40
Hz |
Gamma waves |
Higher mental activity, including perception, problem
solving, fear, and consciousness |
| 13–40 Hz |
Beta waves |
Active, busy or anxious thinking and active concentration,
arousal, cognition |
| 7–13 Hz |
Alpha waves |
Relaxation (while awake), pre-sleep and pre-wake drowsiness |
| 4–7 Hz |
Theta waves |
Theta waves Dreams, deep meditation, REM sleep |
| < 4
Hz |
Delta waves |
Delta waves Deep dreamless sleep, loss of body awareness |
|
