Binaural beats
Encyclopedia
Binaural 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. An on-line sound example of a sound with binaural beats can be found here.
Binaural beats are of interest to neurophysiologists investigating the sense of hearing
.
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.
the human auditory system
analyses interaural time difference
s between both ears inside small frequency ranges, called critical bands. For frequencies below 1000 to 1500 Hz
interaural time differences are evaluated from interaural phase differences between both ear signals.
The perceived sound is also evaluated from the analysis of both ear signals.
If different pure tone
s (sinusoidal signals with different frequencies) are presented to each ear, there will be time dependent phase and time differences between both ears (see figure). The perceived sound depends on the frequency difference between both ear signals:
Binaural beats can also be experienced without headphones, they appear when playing two different pure tones through loudspeakers. The sound perceived is quite similar: with auditory events which move through the room, at low frequency differences, and diffuse sound at slightly bigger frequency differences. At bigger frequency differences apparent localized sound sources appear.
However, it is more effective to use headphones than loudspeakers.
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 approx. 15 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.
Scientific research into binaural beats is very limited. No conclusive studies have been released to support the wilder claims listed above. However, some studies indicate that binaural beats may have a relaxing effect. In absence of positive evidence for a specific effect, however, claimed effects may be attributed to the power of suggestion (the placebo
effect).
. 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. Activated regions include primary sensorimotor and cingulate areas, bilateral opercular premotor areas, bilateral SII, ventral prefrontal cortex, and, subcortically, anterior insula, putamen, and thalamus. Within the cerebellum, vermal regions and anterior hemispheres ipsilateral to the movement became significantly activated. Tracking temporal modulations additionally activated predominantly right prefrontal, anterior cingulate, and intraparietal regions as well as posterior cerebellar hemispheres. 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.
). 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
, theta, alpha
, beta
, or gamma
range of brainwave
frequencies, the brainwaves entrain to or move towards the beat frequency. 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, 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. 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.
(The precise boundaries between ranges vary among definitions, and there is no universally accepted standard.)
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. One theory is to reduce the volume so low that the beating should not even be clearly audible, but this does not seem to be the case (see the next paragraph).
s to produce desired hormone
s. 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; and some people find that half an hour in the theta state can reduce sleeping needs up to four hours; 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 experience
s, 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 also been used successfully for the treatment of addiction
s.
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 randomised, 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 controversy in media was spawned comparing Binaural beats to illegal narcotics.
Binaural
Binaural literally means "having or relating to two ears." Binaural hearing, along with frequency cues, lets humans and other animals determine direction of origin of sounds...
tones are auditory
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
processing artifacts, or apparent sounds, the perception
Perception
Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...
of which arises in the brain for specific physical stimuli
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....
. This effect was discovered in 1839 by Heinrich Wilhelm Dove
Heinrich Wilhelm Dove
Heinrich Wilhelm Dove was a Prussian physicist and meteorologist. He was the father of Alfred and Richard Dove.-Early Years:...
, and earned greater public awareness in the late 20th century based on claims that binaural beats
Beat (acoustics)
In acoustics, a beat is an interference between two sounds of slightly different frequencies, perceived as periodic variations in volume whose rate is the difference between the two frequencies....
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
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...
and sound localization
Sound localization
Sound localization refers to a listener's ability to identify the location or origin of a detected sound in direction and distance. It may also refer to the methods in acoustical engineering to simulate the placement of an auditory cue in a virtual 3D space .The sound localization mechanisms of the...
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
Headphones
Headphones are a pair of small loudspeakers, or less commonly a single speaker, held close to a user's ears and connected to a signal source such as an audio amplifier, radio, CD player or portable Media Player. They are also known as stereophones, headsets or, colloquially, cans. The in-ear...
. 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
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
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. An on-line sound example of a sound with binaural beats can be found here.
Binaural beats are of interest to neurophysiologists investigating the sense of hearing
Hearing (sense)
Hearing is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses...
.
Binaural beats reportedly influence the brain in more subtle ways through the entrainment
Brainwave synchronization
Brainwave entrainment or "brainwave synchronization," is any practice that aims to cause brainwave frequencies to fall into step with a periodic stimulus having a frequency corresponding to the intended brain-state , usually attempted with the use of specialized software...
of brainwaves
Electroencephalography
Electroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
and have been claimed to reduce anxiety and provide other health benefits such as control over pain.
Acoustical background
For sound localizationSound localization
Sound localization refers to a listener's ability to identify the location or origin of a detected sound in direction and distance. It may also refer to the methods in acoustical engineering to simulate the placement of an auditory cue in a virtual 3D space .The sound localization mechanisms of the...
the human auditory system
Auditory system
The auditory system is the sensory system for the sense of hearing.- Outer ear :The folds of cartilage surrounding the ear canal are called the pinna...
analyses interaural time difference
Interaural time difference
The interaural time difference when concerning humans or animals, is the difference in arrival time of a sound between two ears. It is important in the localisation of sounds, as it provides a cue to the direction or angle of the sound source from the head. If a signal arrives at the head from one...
s between both ears inside small frequency ranges, called critical bands. For frequencies below 1000 to 1500 Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
interaural time differences are evaluated from interaural phase differences between both ear signals.
The perceived sound is also evaluated from the analysis of both ear signals.
If different pure tone
Pure tone
A pure tone is a tone with a sinusoidal waveshape.A sine wave is characterized by its frequency, the number of cycles per second—or its wavelength, the distance the waveform travels through its medium within a period—and the amplitude, the size of each cycle...
s (sinusoidal signals with different frequencies) are presented to each ear, there will be time dependent phase and time differences between both ears (see figure). The perceived sound depends on the frequency difference between both ear signals:
- If the frequency difference between the ear signals is lower than some hertz, the auditory system can follow the changes in the interaural time differences. As a result an auditory eventAuditory eventAuditory events describe the subjective perception, when listening to a certain sound situation. This term was introduced by Jens Blauert in the year 1966, in order to distinguish clearly between the physical sound field and the auditory perception of the sound.Auditory events are the central...
is perceived, which is moving through the head. The perceived direction corresponds to the instantaneous interaural time difference. - For slightly bigger frequency differences between the ear signals (more than 10 Hz) the auditory system can no longer follow the changes in the interaural parameters. A diffuse auditory event appears. The sound corresponds to an overlay of both ear signals, which means amplitude and loudness are changing rapidly (see figure in the chapter above).
- For frequency differences between the ear signals of above 30 Hz the cocktail party effectCocktail party effectThe cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. The effect enables most people to talk in a noisy place...
begins to work, and the auditory system is able to analyze the presented ear signals in terms of two different sound sources at two different locations, and two distinct signals are perceived.
Binaural beats can also be experienced without headphones, they appear when playing two different pure tones through loudspeakers. The sound perceived is quite similar: with auditory events which move through the room, at low frequency differences, and diffuse sound at slightly bigger frequency differences. At bigger frequency differences apparent localized sound sources appear.
However, it is more effective to use headphones than loudspeakers.
History
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" (Scientific American, 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
Cognitive neuroscience
Cognitive neuroscience is an academic field concerned with the scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes. It addresses the questions of how psychological/cognitive functions are produced by the brain...
, addressing questions such as how animals locate sounds
Sound localization
Sound localization refers to a listener's ability to identify the location or origin of a detected sound in direction and distance. It may also refer to the methods in acoustical engineering to simulate the placement of an auditory cue in a virtual 3D space .The sound localization mechanisms of the...
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
Cocktail party effect
The cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. The effect enables most people to talk in a noisy place...
").
Oster also considered binaural beats to be a potentially useful medical diagnostic
Medical diagnosis
Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...
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
Parkinson's disease
Parkinson's disease is a degenerative disorder of the central nervous system...
. 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
Menstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
(onset of menstruation and approx. 15 after). This data led Oster to wonder if binaural beats could be used as a tool for measuring relative levels of estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
.
The effects of binaural beats on consciousness were first examined by physicist Thomas Warren Campbell
Thomas Warren Campbell
Thomas Warren Campbell, Jr. , physicis , is the author of the book trilogy My Big TOE. ....
and electrical engineer Dennis Mennerich, who under the direction of Robert Monroe
Robert Monroe
Robert Allen Monroe was a New York radio broadcasting executive who became known for his research into altered consciousness. His 1971 book Journeys Out of the Body is credited with popularizing the term "out-of-body experience".Monroe achieved world-wide recognition as an explorer of human...
sought to reproduce a subjective impression of 4 Hz oscillation that they associated with out-of-body experience
Out-of-body experience
An out-of-body experience is an experience that typically involves a sensation of floating outside of one's body and, in some cases, perceiving one's physical body from a place outside one's body ....
. On the strength of their findings, Monroe created the binaural-beat technology self-development industry by forming The Monroe Institute
The Monroe Institute
The Monroe Institute is a nonprofit education and research organization devoted to the exploration of human consciousness, based in Faber, Virginia, United States. Upwards of 20,000 people are estimated to have attended TMI’s residential Gateway program during its first thirty years, with...
, now a charitable binaural research and education organization.
Unverified claims
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.Scientific research into binaural beats is very limited. No conclusive studies have been released to support the wilder claims listed above. However, some studies indicate that binaural beats may have a relaxing effect. In absence of positive evidence for a specific effect, however, claimed effects may be attributed to the power of suggestion (the placebo
Placebo
A placebo is a simulated or otherwise medically ineffectual treatment for a disease or other medical condition intended to deceive the recipient...
effect).
Physiology
The sensation of binaural beats is believed to originate in the superior olivary nucleus, a part of the brain stemBrain stem
In vertebrate anatomy the brainstem is the posterior part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves...
. 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. Activated regions include primary sensorimotor and cingulate areas, bilateral opercular premotor areas, bilateral SII, ventral prefrontal cortex, and, subcortically, anterior insula, putamen, and thalamus. Within the cerebellum, vermal regions and anterior hemispheres ipsilateral to the movement became significantly activated. Tracking temporal modulations additionally activated predominantly right prefrontal, anterior cingulate, and intraparietal regions as well as posterior cerebellar hemispheres. 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.
Overview
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 entrainmentBrainwave synchronization
Brainwave entrainment or "brainwave synchronization," is any practice that aims to cause brainwave frequencies to fall into step with a periodic stimulus having a frequency corresponding to the intended brain-state , usually attempted with the use of specialized software...
). 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
Dreamachine
The dreamachine is a stroboscopic flicker device that produces visual stimuli. Artist Brion Gysin and William S. Burroughs's "systems adviser" Ian Sommerville created the dreamachine after reading William Grey Walter's book, The Living Brain.-History:In the dreamachine's original form, a...
). However, using alpha frequencies with such stimuli can trigger photosensitive epilepsy
Photosensitive epilepsy
Photosensitive epilepsy is a form of epilepsy in which seizures are triggered by visual stimuli that form patterns in time or space, such as flashing lights, bold, regular patterns, or regular moving patterns.-Symptoms:...
.
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
Delta wave
A delta wave is a high amplitude brain wave with a frequency of oscillation between 0–4 hertz. Delta waves, like other brain waves, are recorded with an electroencephalogram and are usually associated with the deepest stages of sleep , also known as slow-wave sleep , and aid in characterizing the...
, theta, alpha
Alpha Waves
Alpha Waves is an early 3D game that combines labyrinthine exploration with platform gameplay. By most definitions of the genre it could be considered to be the first 3D platform game, released in 1990, 6 years before the genre's seminal classic Super Mario 64...
, beta
Beta wave
Beta wave, or beta rhythm, is the term used to designate the frequency range of human brain activity between 12 and 30 Hz . Beta waves are split into three sections: High Beta Waves ; Beta Waves ; and Low Beta Waves...
, or gamma
Gamma wave
A gamma wave is a pattern of neural oscillation in humans with a frequency between 25 to 100 Hz, though 40 Hz is prototypical.According to a popular theory, gamma waves may be implicated in creating the unity of conscious perception...
range of brainwave
Electroencephalography
Electroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
frequencies, the brainwaves entrain to or move towards the beat frequency. 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, 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. 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.
Brain waves
| Frequency range | Name | Usually associated with: |
|---|---|---|
| > 40 Hz | Gamma waves | Higher mental activity, including perception, problem solving, fear, and consciousness |
| 13–39 Hz | Beta waves | Active, busy or anxious thinking and active concentration, arousal, cognition, and or paranoia |
| 7–13 Hz | Alpha waves | Relaxation (while awake), pre-sleep and pre-wake drowsiness, REM sleep, Dream Dream Dreams are successions of images, ideas, emotions, and sensations that occur involuntarily in the mind during certain stages of sleep. The content and purpose of dreams are not definitively understood, though they have been a topic of scientific speculation, philosophical intrigue and religious... s |
| 4–7 Hz | Theta waves | deep meditation Meditation Meditation is any form of a family of practices in which practitioners train their minds or self-induce a mode of consciousness to realize some benefit.... /relaxation, NREM sleep |
| < 4 Hz | Delta waves | Deep dreamless sleep Sleep Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than... , loss of body awareness |
(The precise boundaries between ranges vary among definitions, and there is no universally accepted standard.)
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
Pink noise
Pink noise or 1/ƒ noise is a signal or process with a frequency spectrum such that the power spectral density is inversely proportional to the frequency. In pink noise, each octave carries an equal amount of noise power...
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. One theory is to reduce the volume so low that the beating should not even be clearly audible, but this does not seem to be the case (see the next paragraph).
Other uses
In addition to lowering the brain frequency to relax the listener, there are other controversial, alleged uses for binaural beats. For example, that by using specific frequencies an individual can stimulate certain glandGland
A gland is an organ in an animal's body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface .- Types :...
s to produce desired hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
s. 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; and some people find that half an hour in the theta state can reduce sleeping needs up to four hours; similar to another other method of achieving a theta state, e.g. meditation
Meditation
Meditation is any form of a family of practices in which practitioners train their minds or self-induce a mode of consciousness to realize some benefit....
;) some use them for lucid dreaming
Lucid dreaming
A lucid dream is a dream in which one is aware that one is dreaming. The term was coined by the Dutch psychiatrist and writer Frederik van Eeden . In a lucid dream, the dreamer can actively participate in and manipulate imaginary experiences in the dream environment. Lucid dreams can seem real and...
and even for attempting out-of-body experience
Out-of-body experience
An out-of-body experience is an experience that typically involves a sensation of floating outside of one's body and, in some cases, perceiving one's physical body from a place outside one's body ....
s, astral projection
Astral projection
Astral projection is an interpretation of out-of-body experience that assumes the existence of an "astral body" separate from the physical body and capable of traveling outside it...
, telepathy
Telepathy
Telepathy , is the induction of mental states from one mind to another. The term was coined in 1882 by the classical scholar Fredric W. H. Myers, a founder of the Society for Psychical Research, and has remained more popular than the more-correct expression thought-transference...
and psychokinesis
Psychokinesis
The term psychokinesis , also referred to as telekinesis with respect to strictly describing movement of matter, sometimes abbreviated PK and TK respectively, is a term...
. However, the role of alpha-wave activity in lucid dreaming is subject to ongoing research).
Alpha-theta brainwave training has also been used successfully for the treatment of addiction
Substance use disorder
Substance use disorders include substance abuse and substance dependence. In DSM-IV, the conditions are formally diagnosed as one or the other, but it has been proposed that DSM-5 combine the two into a single condition called "Substance-use disorder"....
s.
It has been used for the recovery of repressed memories
Repressed memory
Repressed memory is a hypothetical concept used to describe a significant memory, usually of a traumatic nature, that has become unavailable for recall; also called motivated forgetting in which a subject blocks out painful or traumatic times in one's life...
, 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 randomised, 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 controversy in media was spawned comparing Binaural beats to illegal narcotics.
Example
See also
- Brainwave synchronizationBrainwave synchronizationBrainwave entrainment or "brainwave synchronization," is any practice that aims to cause brainwave frequencies to fall into step with a periodic stimulus having a frequency corresponding to the intended brain-state , usually attempted with the use of specialized software...
- ElectroencephalographyElectroencephalographyElectroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
- Event-related potentialEvent-related potentialAn event-related potential is any measured brain response that is directly the result of a thought or perception. More formally, it is any stereotyped electrophysiological response to an internal or external stimulus....
- Evoked potentialEvoked potentialAn evoked potential is an electrical potential recorded from the nervous system of a human or other animal following presentation of a stimulus, as distinct from spontaneous potentials as detected by electroencephalography or electromyography .Evoked potential amplitudes tend to be low, ranging...
- GnauralGnauralGnaural is brainwave entrainment software for Windows, Mac OS X, and Linux licensed under the GNU General Public License. Gnaural is free software for creating binaural beats intended to be used as personal brainwave synchronization software, for scientific research, or by professionals...
- Hemi-SyncHemi-SyncHemi-Sync is a trademarked brand name for a patented process used to create audio patterns containing binaural beats, which are commercialized in the form of audio CDs. Interstate Industries Inc., created by Hemi-Sync founder Robert Monroe, is the owner of the Hemi-Sync technology. Hemi-Sync is...
- Human enhancementHuman enhancementHuman enhancement refers to any attempt to temporarily or permanently overcome the current limitations of the human body through natural or artificial means...
- Induced activity
- Intelligence amplificationIntelligence amplificationIntelligence amplification refers to the effective use of information technology in augmenting human intelligence...
- Lucid dream
- Mind machineMind machineA mind machine uses pulsing rhythmic sound and/or flashing light to alter the brainwave frequency of the user...
- Neural oscillation
- NeurofeedbackNeurofeedbackNeurofeedback , also called neurotherapy, neurobiofeedback or EEG biofeedback is a type of biofeedback that uses realtime displays of electroencephalography or functional magnetic resonance imaging to illustrate brain activity, often with a goal of controlling central nervous system activity...
- Ongoing brain activity
- Power-Nap Recording
- Schumann resonances