History of Binaural Beats
Discovered in 1839 by German researcher Heinrich_Wilhelm_Dove, at first were hired as an additional form of the monaural beat, but after further investigation, it was discovered that the binaural beat was produced by the brain itself.
When the brain receives different signals from the two ears tries to mix them as if they were two sounds perceived together. This is because the brain has to rework the tones and binaural beats using a different part of the brain compared to monaural beats. This is the reason why the technique of binaural beats is unique and special in comparison to other methods of induction.
In order to produce binaural beats, the brain must be able to identify the phase angle between the two tones. Unfortunately, the cerebral apparatus has difficulty in identifying the phase relations with frequencies above 900 Hertz, so that at higher frequencies the binaural beat becomes imperceptible although still effective up to around 1500 Hz.
When the difference of the frequencies of the two tones is over at 25 Hertz, the brain is not unable to determine the phase relationship between them, so that the two tones are perceived as separate in contraposition to the beats combined.
Even when the brain produces binaural beats, the modulation depth and much lower than the monaural beat. This is the reason for which it is often difficult to perceive binaural beats even at 440 Hertz, which is the optimal frequency of detection. These are the limitations of a normal human brain, a brain that suffered neurological damage may not be able to perceive the binaural beats.
Unlike monaural beats, binaural beats maintain the full effect even if the two tones are of different amplitude and can be used even if the carrier is below the threshold of human hearing. In this case, the effect is however minor.
Unfortunately, the binaural beats produce only small evoked potentials in the auditory cortex of the brain that is responsible for the BWE (brainwave entrainment).
A study by Dale S. Foster in 1990 concluded that although the binaural beats produce BWE, they would not be significant enough in themselves. In his study, a sound generated artificially produces more alpha waves of a binaural beat of 10.5 Hz.
They can be very hypnotics, this is mainly due to the Ganzfeld effect, which is a state of reduced sensory stimulation, usually produced by covering the eyes of a subject lying, with two half ping-pong balls, on which is aimed a red light, and spreading through a pair of headphones the white noise.
Since that require the use of both hemispheres of the brain, the binaural beats can also induce cerebral synchronization, “whole-brain effect”, which is an effect boasted by The Monroe Institute (TMI) and by others who have given of proper names to their products.
Nevertheless, other forms of induction, such as meditation itself, can produce hemispheric synchronization.