Brainwave synchronization
Encyclopedia
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 (for example, to induce sleep), usually attempted with the use of specialized software
. It purportedly depends upon a "frequency following" response on the assumption that the human brain has a tendency to change its dominant EEG
frequency towards the frequency of a dominant external stimulus. Such a stimulus is often aural, as in the case of binaural
or monaural beats
and isochronic tones
, or else visual, as with a dreamachine
, a combination of the two with a mind machine
, or even electromagnetic radiation
.
noting in 200 AD the effects of flickering sunlight generated by a spinning wheel. In the 1930s and '40s, with then-new EEG equipment and strobe lights, William Grey Walter
performed some of the first scientific research on the subject. Later, in the 1960s and '70s, interest in altered states led some artists to become interested in the subject, most notably Brion Gysin
who, along with a Cambridge math student, invented the Dreamachine
. From the 1970s to date there have been numerous studies and various machines built that combine light and sound. These efforts were aided by continued development of micro-circuitry and other electronic breakthroughs which allowed for ever more sophisticated equipment. One of the more frequently noted scientific results claimed for brainwave entrainment was the discovery of binaural beats, published in Scientific American in 1973 by Gerald Oster. However, Oster's research actually makes no mention of brainwaves. With the development of isochronic tones by Arturo Manns, combined with more sophisticated equipment, these discoveries led to many attempts to use claimed brainwave entrainment techniques in the treatment of numerous psychological and physiological conditions.
may be achieved when audio signal
s are introduced to the brain causing a response directly related to the frequency of the signal introduced, called binaural beats. Two tones close in frequency generate a beat frequency at the difference of the frequencies, which is generally subsonic
. For example, a 495 Hz tone and 505 Hz tone will produce a subsonic 10 Hz beat, roughly in the middle of the alpha range. The "carrier frequency" (e.g., the 500 Hz in the example above), is also said by some to affect the quality of the transformative experience. Note that this effect is achieved without either ear hearing the pulse when headphones are used. Instead, the brain produces the pulse by combining the two tones. Each ear hears only a steady tone. Although some have claimed that these frequencies do provide help in treating certain medical conditions, there is not a wide acceptance by the medical community to adopt the practice of brainwave entrainment for emotional/mental disorders. A fixed, constant frequency of synchronization is less helpful than techniques such as classical neurofeedback
or learning meditation
, which naturally generate brainwave frequencies that differ from person to person and may vary from minute to minute.
. Binaural beats are not the same as monaural beats. Binaural beats are perceived by presenting two different tones at slightly different pitches (or frequencies) separately into each ear. This effect is produced in the brain, not in the ears as with monaural beats. It is produced by the neural output from the ears and created within the olivary body within the brain, in its attempt to "locate" the direction of the sound based on phase.
Only monaural beats are the result of the arithmetic (vector) sum of the waveforms of the two tones as they add or subtract from one another, becoming louder and quieter and louder again.
Monaural and binaural beats are rarely encountered in nature, but in man-made objects, monaural beats occur frequently. For example, two large engines running at slightly different speeds will send "surges" of vibrations through the deck of a ship or jet plane. The lower pitched tone is called the carrier and the upper tone is called the offset.
Monaural beats occur in the open air and external to the ears. For example, when two guitar strings of slightly different frequencies are plucked simultaneously, monaural beats strike the ear as beats and therefore excite the thalamus, an action crucial for entrainment. Binaural beats played through loudspeakers become monaural beats.
To hear monaural beats, both tones must be of the same amplitude. However binaural beats can be heard when the tones have different amplitudes. They can even be heard if one of the tones is below the hearing threshold. Noise reduces the perceived volume of monaural beats whereas noise actually increases the loudness of binaural beats.
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 to fall into step with a periodic stimulus having a frequency corresponding to the intended brain-state (for example, to induce sleep), usually attempted with the use of specialized software
Comparison of brainwave entrainment software
Brainwave entrainment is the practice of entraining one's brainwaves to a desired frequency, by means of a periodic stimulus with corresponding frequency. The stimulus can be aural as in the case of binaural or monaural beats and isochronic tones, visual as with a dreamachine, a combination of the...
. It purportedly depends upon a "frequency following" response on the assumption that the human brain has a tendency to change its dominant EEG
EEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
frequency towards the frequency of a dominant external stimulus. Such a stimulus is often aural, as in the case of binaural
Binaural beats
Binaural beats or binaural tones are auditory processing artifacts, or apparent sounds, the perception of which arises in the brain for specific physical stimuli...
or monaural beats
Monaural beats
Monaural beats are used for brainwave entrainment in which two tones which would be used binaural beats are played in each channel resulting in a stronger stimulus. With monaural beats, the interference pattern that produces the beat is outside the brain so headphones are not required...
and isochronic tones
Isochronic tones
Isochronic tones are regular beats of a single tone used for brainwave entrainment. Similar to monaural beats, the interference pattern that produces the beat is outside the brain so headphones are not required for entrainment to be effective. They differ from monaural beats, which are constant...
, or else visual, as with a 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...
, a combination of the two with a mind machine
Mind machine
A mind machine uses pulsing rhythmic sound and/or flashing light to alter the brainwave frequency of the user...
, or even electromagnetic radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
.
History
Enthusiasts of brainwave entrainment claim that it has been noted or used in one form or another for centuries (long before the invention of EEG equipment), from shamanistic societies' use of drum beats to PtolemyPtolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...
noting in 200 AD the effects of flickering sunlight generated by a spinning wheel. In the 1930s and '40s, with then-new EEG equipment and strobe lights, William Grey Walter
William Grey Walter
W. Grey Walter was a neurophysiologist and robotician.-Overview:Walter was born in Kansas City, Missouri, in 1910. His ancestry was German/British on his father's side, and American/British on his mother's side. He was brought to England in 1915, and educated at Westminster School and afterwards...
performed some of the first scientific research on the subject. Later, in the 1960s and '70s, interest in altered states led some artists to become interested in the subject, most notably Brion Gysin
Brion Gysin
Brion Gysin was a painter, writer, sound poet, and performance artist born in Taplow, Buckinghamshire.He is best known for his discovery of the cut-up technique, used by his friend, the novelist William S. Burroughs...
who, along with a Cambridge math student, invented the 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...
. From the 1970s to date there have been numerous studies and various machines built that combine light and sound. These efforts were aided by continued development of micro-circuitry and other electronic breakthroughs which allowed for ever more sophisticated equipment. One of the more frequently noted scientific results claimed for brainwave entrainment was the discovery of binaural beats, published in Scientific American in 1973 by Gerald Oster. However, Oster's research actually makes no mention of brainwaves. With the development of isochronic tones by Arturo Manns, combined with more sophisticated equipment, these discoveries led to many attempts to use claimed brainwave entrainment techniques in the treatment of numerous psychological and physiological conditions.
Binaural beats
Binaural beats deserve special mention because of the manner in which the desired frequencies are obtained. Brainwave entrainmentEntrainment (physics)
Entrainment has been used to refer to the process of mode locking of coupled driven oscillators, which is the process whereby two interacting oscillating systems, which have different periods when they function independently, assume a common period...
may be achieved when audio signal
Audio signal
An audio signal is an analog representation of sound, typically as an electrical voltage. Audio signals may be synthesized directly, or may originate at a transducer such as a microphone, musical instrument pickup, phonograph cartridge, or tape head. Loudspeakers or headphones convert an electrical...
s are introduced to the brain causing a response directly related to the frequency of the signal introduced, called binaural beats. Two tones close in frequency generate a beat frequency at the difference of the frequencies, which is generally subsonic
Infrasound
Infrasound is sound that is lower in frequency than 20 Hz or cycles per second, the "normal" limit of human hearing. Hearing becomes gradually less sensitive as frequency decreases, so for humans to perceive infrasound, the sound pressure must be sufficiently high...
. For example, a 495 Hz tone and 505 Hz tone will produce a subsonic 10 Hz beat, roughly in the middle of the alpha range. The "carrier frequency" (e.g., the 500 Hz in the example above), is also said by some to affect the quality of the transformative experience. Note that this effect is achieved without either ear hearing the pulse when headphones are used. Instead, the brain produces the pulse by combining the two tones. Each ear hears only a steady tone. Although some have claimed that these frequencies do provide help in treating certain medical conditions, there is not a wide acceptance by the medical community to adopt the practice of brainwave entrainment for emotional/mental disorders. A fixed, constant frequency of synchronization is less helpful than techniques such as classical neurofeedback
Neurofeedback
Neurofeedback , 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...
or learning 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....
, which naturally generate brainwave frequencies that differ from person to person and may vary from minute to minute.
Monaural beats
Binaural beats were first discovered in 1839 by H. Dove, a German experimenter. At that time, binaural beats were considered to be a special case of monaural beatsMonaural beats
Monaural beats are used for brainwave entrainment in which two tones which would be used binaural beats are played in each channel resulting in a stronger stimulus. With monaural beats, the interference pattern that produces the beat is outside the brain so headphones are not required...
. Binaural beats are not the same as monaural beats. Binaural beats are perceived by presenting two different tones at slightly different pitches (or frequencies) separately into each ear. This effect is produced in the brain, not in the ears as with monaural beats. It is produced by the neural output from the ears and created within the olivary body within the brain, in its attempt to "locate" the direction of the sound based on phase.
Only monaural beats are the result of the arithmetic (vector) sum of the waveforms of the two tones as they add or subtract from one another, becoming louder and quieter and louder again.
Monaural and binaural beats are rarely encountered in nature, but in man-made objects, monaural beats occur frequently. For example, two large engines running at slightly different speeds will send "surges" of vibrations through the deck of a ship or jet plane. The lower pitched tone is called the carrier and the upper tone is called the offset.
Monaural beats occur in the open air and external to the ears. For example, when two guitar strings of slightly different frequencies are plucked simultaneously, monaural beats strike the ear as beats and therefore excite the thalamus, an action crucial for entrainment. Binaural beats played through loudspeakers become monaural beats.
To hear monaural beats, both tones must be of the same amplitude. However binaural beats can be heard when the tones have different amplitudes. They can even be heard if one of the tones is below the hearing threshold. Noise reduces the perceived volume of monaural beats whereas noise actually increases the loudness of binaural beats.
Isochronic tones
"Isochronic tones are evenly spaced tones which turn on and off quickly."Audio–visual entrainment
Audio–visual entrainment (AVE), a subset of brainwave entrainment, uses flashes of lights and pulses of tones to guide the brain into various states of brainwave activity. AVE devices are often termed light and sound machines or mind machines. Altering brainwave activity may aid in the treatment of psychological and physiological disorders.See also
- Comparison of brainwave entrainment softwareComparison of brainwave entrainment softwareBrainwave entrainment is the practice of entraining one's brainwaves to a desired frequency, by means of a periodic stimulus with corresponding frequency. The stimulus can be aural as in the case of binaural or monaural beats and isochronic tones, visual as with a dreamachine, a combination of the...
- Binaural beatsBinaural beatsBinaural beats or binaural tones are auditory processing artifacts, or apparent sounds, the perception of which arises in the brain for specific physical stimuli...
- 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...
- Mind machineMind machineA mind machine uses pulsing rhythmic sound and/or flashing light to alter the brainwave frequency of the user...
- 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...
- 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...
- Bilateral soundBilateral SoundBilateral sound is a type of bilateral stimulation used in eye movement desensitization and reprocessing in the same manner as eye movement. It has been reported to enhance visualization and hypnosis, but this has received little attention in research. Essentially, the sound moves back and forth...
- 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...
- Emotiv SystemsEmotiv SystemsEmotiv Systems is an Australian electronics company developing brain–computer interfaces based on electroencephalography technology. The company was founded in 2003 by four scientists and executives: neuroscientist Professor Allan Snyder, chip-designer Neil Weste, and technology entrepreneurs Tan...
- Intelligence amplificationIntelligence amplificationIntelligence amplification refers to the effective use of information technology in augmenting human intelligence...
- Music therapyMusic therapyMusic therapy is an allied health profession and one of the expressive therapies, consisting of an interpersonal process in which a trained music therapist uses music and all of its facets—physical, emotional, mental, social, aesthetic, and spiritual—to help clients to improve or maintain their...
- Neural oscillationsNeural oscillationsNeural oscillation is rhythmic or repetitive neural activity in the central nervous system. Neural tissue can generate oscillatory activity in many ways, driven either by mechanisms localized within individual neurons or by interactions between neurons...
- 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...
- 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....
- Induced activity
- DreamachineDreamachineThe 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...
- Ongoing brain activity
- Trancranial alternating-current stimulation
- I-DoserI-DoserI-Doser is an application for the playback of proprietary audio content. The developer claims the separately purchasable content aims to simulate specific mental states through the use of binaural beats, and much of it is named after prohibited recreational drugs...
External links
- Auditory Driving as Ritual Technology: A Review and Analysis – Overview of entrainment techniques
- Brainwave Entrainment to External Rhythmic Stimuli – Interdisciplinary research and clinical perspectives symposium (Stanford University)
- http://www.stanford.edu/group/brainwaves/2006/theclinicalguidetosoundandlight.pdf The Clinical Guide to Sound and Light By Thomas Budzynski, PhD
- Squareeater Free entrainment resource using binaural audio and stroboscopic visual effects
- Virtual Light & Sound Machine Psychologist simulates visual brainwave entrainment using flashes on computer monitor.
- Open-Source Brainwave Software Brainwave Entrainment Mindmachine with binaural beats, flashing screen and Neurofeedback
- Brainwave College Non-profit site teaching brainwave entrainment science, including downloadable audio entrainment sessions