Binaural beats are an auditory stimulus that influences the electrical activity of the brain. This stimulus is sensed when different, yet close in frequency tones are played through headphones. When the differing tones enter each ear, the listener senses the difference in tone as a wave-like “beat” that is measured in hertz. This generated tone originates from the medial superior olivary nucleus located in the area of the brain responsible for processing signals sent from each ear.
Binaural Beats work only when using headphones. You may listen to them as background with other music, or by themselves. It is not necessary to listen with a high volume, however they should be loud enough to hear the waving sound. You will feel the effects of the binaural beats after approximately 10-15 minutes of listening.
The concept of frequency following response is that if one receives a stimulus with a frequency in the range of brain waves, the predominant brain wave frequency is said to be likely to move towards the frequency of the stimulus (a process called entrainment). In addition, binaural beats have been credibly documented to activate various sites in the brain creating desired effects
Perceived human hearing is limited to the range of frequencies from 20 Hz to 20,000 Hz, but the frequencies of human brain waves are below about 40 Hz. To account for this lack of perception, binaural beat frequencies are used. Beat frequencies of 40 Hz have been produced in the brain with binaural sound and measured experimentally.
When the perceived beat frequency corresponds to the delta, theta, alpha, beta, or gamma range of brainwave frequencies, the brainwaves entrain to or move towards the beat frequency. For example, if a 210 Hz frequency is played into the right ear and a 220 Hz one into the left ear, the brain is entrained towards the beat frequency 10 Hz, in the alpha range. Since alpha range is associated with relaxation, this has a relaxing effect or if in the beta range, more alertness. An experiment with binaural sound stimulation using beat frequencies in the Beta range on some participants and Delta/Theta range in other participants, found better vigilance performance and mood in those on the awake alert state of Beta range stimulation.
Binaural beat stimulation has been used fairly extensively to induce a variety of states of consciousness, and there has been some work done in regards to the effects of these stimuli on relaxation, focus, attention, and states of consciousness.
The dominant frequency determines your current state. For example, if in someone’s brain alpha waves are dominating, they are in the alpha state. However, other frequencies will also be present, albeit with smaller amplitudes.
The brain entraining is more effective if the entraining frequency is close to the user’s starting dominant frequency. Therefore, it is suggested to start with a frequency near to one’s current dominant frequency (likely to be about 20 Hz or less for a waking person), and then slowly decreasing/increasing it towards the desired frequency.
Some people find pure sine waves unpleasant, so a white noise or another background (e.g. natural sounds such as rain) can also be mixed in. In addition to that, as long as the beat is audible, increasing the volume should not necessarily improve the effectiveness, therefore using a low volume is usually suggested.
In addition to lowering the brain frequency to relax the listener, there are other controversial uses for binaural beats. For example, using specific frequencies an individual can stimulate certain glands to produce desired hormones.
Other uses include reducing learning time and sleeping needs. For example, theta waves are thought to improve learning, since children, who have stronger theta waves, and remain in this state for a longer period of time than adults, usually learn faster than adults; and some people find that half an hour in the theta state can reduce sleeping needs up to four hours; similar to another method of achieving a theta state some use them for lucid dreaming and even for astral projection, and pain relief.
Alpha-theta brainwave training has also been used successfully for the treatment of addictions. It has been used for the recovery of repressed memories, but as with other techniques this can lead to false memories.
An uncontrolled pilot study of Delta binaural beat technology over 60 days has shown positive effect on self-reported psychologic measures, especially anxiety. There was significant decrease in trait anxiety, an increase in quality of life, and a decrease in insulin-like growth factor-1 and dopamine and has been successfully shown to decrease mild anxiety. A randomized, controlled study concluded that binaural beat audio could lessen hospital acute pre-operative anxiety.
Another claimed effect for sound induced brain synchronization is enhanced learning ability. It was proposed in the 1970s that induced alpha brain waves enabled students to assimilate more information with greater long term retention. In more recent times has come more understanding of the role of theta brain waves in behavioural learning. The presence of theta patterns in the brain has been associated with increased receptivity for learning and decreased filtering by the left hemisphere. Based on the association between theta activity (4–7 Hz) and working memory performance, biofeedback training suggests that normal healthy individuals can learn to increase a specific component of their EEG activity, and that such enhanced activity may facilitate a working memory task and to a lesser extent focused attention.
A small media controversy was spawned in 2010 by an Oklahoma Bureau of Narcotics official comparing binaural beats to illegal narcotics, and warning that interest in websites offering binaural beats could lead to drug use.