Binaural [bahy-nawr-uhl] beats or binaural tones are auditory processing artifacts, or apparent sounds, the perception of which arises in the brain for specific physical stimuli. This effect was discovered in 1839 by Heinrich Wilhelm Dove, and earned greater public awareness in the late 20th century based on claims that binaural beats could help induce relaxation, meditation, creativity and other desirable mental states. The effect on the brainwaves depends on the difference in frequencies of each tone, for example, if 300 Hz was played in one ear and 310 in the other, then the Binaural beat would have a frequency of 10 Hz.
The brain produces a phenomenon resulting in low-frequency pulsations in the amplitude and sound localization 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 frequencies of the tones must be below 1,000 hertz for the beating to be noticeable. The difference between the two frequencies must be small (less than or equal to 30 Hz) for the effect to occur; otherwise, the two tones will be heard separately and no beat will be perceived. Binaural beats reportedly influence the brain in more subtle ways through the entrainment of brainwaves and have been claimed to reduce anxiety and provide other health benefits such as control over pain.
Heinrich Wilhelm Dove discovered binaural beats in 1839. While research about them continued after that, the subject remained something of a scientific curiosity until 134 years later, with the publishing of Gerald Oster’s article ‘Auditory Beats in the Brain’ (1973). Oster’s article identified and assembled the scattered islands of relevant research since Dove, offering fresh insight (and new laboratory findings) to research on binaural beats. In particular, Oster saw binaural beats as a powerful tool for cognitive and neurological research, addressing questions such as how animals locate sounds in their three-dimensional environment, and also the remarkable ability of animals to pick out and focus on specific sounds in a sea of noise (which is known as the ‘cocktail party effect’).
Oster also considered binaural beats to be a potentially useful medical diagnostic tool, not merely for finding and assessing auditory impairments, but also for more general neurological conditions (binaural beats involve different neurological pathways than ordinary auditory processing). For example, Oster found that a number of his subjects that could not perceive binaural beats, suffered from Parkinson’s disease. In one particular case, Oster was able to follow the subject through a week-long treatment of Parkinson’s disease; at the outset the patient could not perceive binaural beats; but by the end of the week of treatment, the patient was able to hear them.
In corroborating an earlier study, Oster also reported gender differences in the perception of beats. Specifically, women seemed to experience two separate peaks in their ability to perceive binaural beats—peaks possibly correlating with specific points in the menstrual cycle (onset of menstruation and approximately 15 days after). This data led Oster to wonder if binaural beats could be used as a tool for measuring relative levels of estrogen.
The effects of binaural beats on consciousness were first examined by physicist Thomas Warren Campbell and electrical engineer Dennis Mennerich, who under the direction of Robert Monroe sought to reproduce a subjective impression of 4 Hz oscillation that they associated with out-of-body experience. On the strength of their findings, Monroe created the binaural-beat technology self-development industry by forming The Monroe Institute, now a charitable binaural research and education organization.
There have been a number of claims regarding binaural beats, among them that they may simulate the effect of recreational drugs, help people memorize and learn, stop smoking, help dieting, tackle erectile dysfunction and improve athletic performance. However, scientific research into binaural beats is very limited. No conclusive studies have been released to support marketing claims made about binaural beats.
The sensation of binaural beats is believed to originate in the superior olivary nucleus, a part of the brain stem. They appear to be related to the brain’s ability to locate the sources of sounds in three dimensions and to track moving sounds, which also involves inferior colliculus (IC) neurons. Regarding entrainment, the study of rhythmicity provides insights into the understanding of temporal information processing in the human brain. Auditory rhythms rapidly entrain motor responses into stable steady synchronization states below and above conscious perception thresholds. A study of aphasic subjects who had a severe stroke versus normal subjects showed that the aphasic subject could not hear the binaural beats whereas the normal subjects could.
Binaural beats may influence functions of the brain in ways besides those related to hearing. This phenomenon is called frequency following response. The concept 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 relate to both spatial perception & stereo auditory recognition, and, according to the frequency following response, activation of various sites in the brain.
The stimulus does not have to be aural; it can also be visual or a combination of aural and visual (one such example would be Dreamachine). However, using alpha frequencies with such stimuli can trigger photosensitive epilepsy.
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 (1-3 hertz), theta (4–7 Hz), alpha (8–12 Hz) beta (13–39 Hz), or gamma (>40 Hz) brainwaves, the brainwaves entrain to or move towards the beat frequency (the precise boundaries between ranges vary among definitions, and there is no universally accepted standard). For example, if a 315 Hz sine wave is played into the right ear and a 325 Hz one into the left ear, the brain is entrained towards the beat frequency 10 Hz (alpha wave). 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. Studies have shown that with repeated training to distinguish close frequency sounds that a plastic reorganization of the brain occurs for the trained frequencies and is capable of asymmetric hemispheric balancing (there is no need for both hemispheres to mirror each other and replicate functionality; instead, an asymmetric approach allows distributed functionally and functional adaptation by either hemisphere).
Gamma waves are associated with higher mental activity, including perception, problem solving, fear, and consciousness. Beta waves are associated with active, busy or anxious thinking and active concentration, arousal, cognition, and or paranoia. Alpha waves are associated with relaxation (while awake), pre-sleep and pre-wake drowsiness, REM sleep, and dreaming. Theta waves are associated with deep meditation/relaxation, non-REM sleep. Delta waves are associated with deep dreamless sleep, and loss of body awareness.
The dominant frequency determines your current state. For example, if in someone’s brain alpha waves are dominating, they are in the alpha state (this happens when one is relaxed but awake). However, also other frequencies will 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 pink noise or another background (e.g. natural sounds such as river noises) can also be mixed with them. 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 (or to raise it to help focusing), there are other controversial, alleged uses for binaural beats. For example, that by using specific frequencies an individual can stimulate certain glands to produce desired hormones. Beta-endorphin has been modulated in studies using alpha-theta brain wave training, and dopamine with binaural beats.
Among other alleged uses, there are reducing learning time and sleeping needs (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; similar to another other method of achieving a theta state, e.g. meditation) some use them for lucid dreaming and even for attempting out-of-body experiences, astral projection, telepathy and psychokinesis. However, the role of alpha-wave activity in lucid dreaming is subject to ongoing research).
Alpha-theta brainwave training has 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.
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. Current research seeks to understand the role of theta brain waves in behavioral learning. The presence of theta patterns in the brain has been associated with increased receptivity for learning and decreased filtering by the left hemisphere.
The Daily Omnivore 
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