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.
Want to know more about Brainwaves? Click
here!
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Entrainment
Review |
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Fig. 1
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| 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.
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Brainwave
Entrainment Methods |
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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 patent-pending feature
completely unique to Mind WorkStation. 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.
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Further
Reading |
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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.
Shealy,
N., Cady, R., Cox, R., Liss, S., Clossen, W., Veehoff, D. "A
Comparison of Depths of Relaxation Produced by Various Techniques
and Neurotransmitters by Brainwave Entrainment" - Shealy
and Forest Institute of Professional Psychology A study done
for Comprehensive Health Care, Unpublished.
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.
See the Further Reading page
for more.
Also see the list of Peer
Reviewed, Placebo-Controlled Studies

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