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Entrainment Methods

What are Brainwaves? | Stimulating the Brain | Methods | A Brief History

Many people have asked to know more about our unique approach to brainwave entrainment. On this page we are going to attempt to explain how some of these techniques work and why we use them. It may get a bit technical at times, but should be informative. If you have any further questions please email us or visit our online community.

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Entrainment Review
EEG Recording. Spectrogram View (4-30), middle of an Alpha session

Before we start, let's make sure we have a handle on some of the basic concepts behind brainwave entrainment.

Any Stimulus Can Be Used

Most people's only experience with brainwave entrainment has been through binaural beats, so it is important to note that they are not the only way the brain can be entrained. In fact, the brain is affected by any kind of rhythmic stimuli. Clicks, drum beats, light flickers, and even physical vibrations or electric pulses have all been proven to effectively entrain the brain. However, to have a significant effect, the stimuli must configured correctly and be precisely timed.

For more information on how entrainment occurs, click here.

Embedded Entrainment

Using a modern tool like Mind WorkStation, there are ways of embedding the precise and rapid modulations into sound files or white noise, without distorting the music. This is important because many people will find audible beats difficult to listen to at first.

Without Headphones

Some entrainment methods do not rely on speaker assignments, and therefore can be used without headphones or any special speaker assignments. For veteran users of brainwave entrainment, this may seem strange since headphones have always been a traditional part of the brain training experience. The reality of the matter is that headphones have never been required for use with anything except binaural beats. Monaural beats can be used very effectively without headphones. So can pulses, clicks and light stimulation. In fact, many ancient cultures used drums to enter deeply relaxed "trances" during Shamanic rituals. Though they may not have called it brainwave entrainment, there is evidence that the rhythmic stimulus of the drum could have been the cause of the "trance-like" states reported during such rituals.

EEG Recording. Spectrogram View (4-30), middle of an Alpha session

Brainwave Entrainment Methods

Mind WorkStation is capable of producing all known forms of audio and visual brainwave entrainment, including some unique methods specifically developed for this program.

Below are the explanations for some of the methods available:

Binaural Beats

The most well known form of brainwave entrainment is binaural beats, where a slightly different tone is presented into each ear. When pure tones are mixed together, their waveforms add and subtract from one another, resulting in a pulse. In the case of binaural beats, the two tones are mixed by the brain itself (one in each ear). The pulses, called "beats", formed by mixing these tones is what causes entrainment to occur.

Monaural Beats

Monaural beats are based on the same concept as binaural beats - combining two tones to form a beat. The difference is that monaural beats are formed when two tones combine digitally or naturally before the sound reaches the ears, as opposed to combining in the brain like binaural beats.

Harmonic "Box" Constructions

"Box" constructions use a combination of both monaural and binaural beats. For the first time, the "Harmonic Box X" construction invented by James Mann is available natively in Mind WorkStation (previously, complex workarounds and session configurations were required to form this construction).

Isochronic Tones

Isochronic tones are evenly spaced tone pulses. Unlike binaural and monaural beats, isochronic tones do not rely on the combination of two tones - the "beat" is created manually by turning a tone on and off. Widely regarded as the most effective tone-based method, isochronic beats produce very strong cortical responses in the brain. Many people who do not respond well to binaural beats often respond very well to isochronic tones.

Here is an example of what an isochronic beat would look like:

Pitch Panning

Pitch panning is a method used to create binaural beats using a sound file or a single tone as the "carrier". This filter modulates the pitch slightly up and down, and at the same time pans the modulation between stereo sides, such that one side will have a slightly higher pitch while the other side has a pitch that is slightly lower.

The result is a kind of spatial positioning that, when listened to through stereo headphones, produces a similar effect to binaural beats. However, unlike binaural beats, you have the option of only using a single sound source (one tone, not two) or even a sound file.

Modulations & Audio Filtering

Modulating sound is a way to produce brainwave entrainment using something as complex as a musical track. In effect, this is "embedding" brainwave entrainment into the audio. Any sound can be used, from nature sounds to white noise to a full classical symphony.

Modulation works by rhythmically adjusting a component in the sound. For example, volume modulation would be used to increase and decrease the volume to create the rhythmic stimulus necessary for entrainment to occur.

Below is an example of a single filter (volume modulation) applied to music:

Frequency Band Selection

Frequency band selection is a patented feature completely unique to Transparent products. The problem with modulation (above) is that it can often distort the audio, particularly when used with music or certain nature sounds like rain. Frequency band selection solves this problem by selectively modulating certain parts of an audio file, instead of the whole of it.

To give you an idea of how this works, below is an outline of the approximate frequency ranges of various instruments. The brainwave entrainment is embedded into a lower frequency range only - affecting parts of the bass and cello, but leaving the viola and violin alone. This illustrates how frequency band selection can be used to affect only one part of a sound file. Multiple frequency bands can also be selected, but for simplicity the below example only uses one.

Frequency band selection is an important advancement, allowing entrainment to be embedded into any sound file with virtually no negative effect on the existing audio. Additionally, the effectiveness of the session is actually increased because it allows for much higher intensity levels.

AudioStrobe Glasses (eyesets)

LED glasses are used to deliver rapid flashes of light to entrain the brain. In most cases, the eyes are closed and the light will shine through the eyelids because of the closeness of the LEDs. However, in some cases eyes-open stimulation is useful and some types of glasses do support it.

Mind WorkStation communicates with LED glasses through AudioStrobe signals, which are a standard in the industry. Most mind machines are AudioStrobe compatible, and AudioStrobe decoders with glasses can be purchased.

Screen Flashing

Screen flashing uses the computer screen to deliver there required pulses of light. Although glasses are the best way to entrain the brain using light, screen flashing can be useful in the absence of glasses. In Mind WorkStation the flashing can also be used on top of 3D visualizations, creating a subtle flash that is comfortable even with eyes open.

"Pulsed" Visualizations

Most visual plugins response to beats and rhythm. How they respond will differ between plugins, but many are capable of providing a very subtle entrainment stimulus. This is purely experimental, however, since nothing like this has ever been used in clinical studies.

Left / Right Hemisphere Stimulation

Each ear is connected to the opposite brain hemisphere, so this presents the opportunity to stimulate each hemisphere in different ways. Many modern brainwave entrainment protocols require this flexibility. For example, some will stimulate the right hemisphere with SMR or Alpha while stimulating the left hemisphere with Beta. Mind WorkStation supports left/right hemispheric stimulation natively, making this process a lot easier.

 

Further Reading

Bermer, F. "Cerebral and cerebellar potentials." Physiological Review, 38, 357-388.

Chatrian, G., Petersen, M., Lazarte, J. "Responses to Clicks from the Human Brain: Some Depth Electrographic Observation." Electroencephalography and Clinical Neurophysiology, 12: 479-487

Gontgovsky, S., Montgomery, D. "The Physiological Response to "Beta Sweep" Entrainment." Proceedings AAPB Thirteenth Anniversary Annual Meeting, 62-65.

Oster, G. "Auditory beats in the brain." Scientific American, 229, 94-102.

Siever, D. "Isochronic Tones and Brainwave Entrainment." Unpublished, but available through his book the Rediscovery of Audio-Visual Entrainment.

Walter, V. J. & Walter, W. G. "The central effects of rhythmic sensory stimulation." Electroencephalography and Clinical Neurophysiology, 1, 57-86.

Go to the Research & Further Reading Section