Extracted Public Domain Article
The Theory of Brainwave Entrainment
EEG and the brain's state
EEG (Electroencephalography) technology is used to measure brain's electrical
vibrations from the surface of the scalp. The resulting EEG pattern will
contain frequency elements mainly below 30Hz. The frequencies are categorized
into four states as follows:
State Frequency Range State of Mind
Delta 0.5 Hz - 4 Hz Deep sleep
Theta 4 Hz - 8 Hz Drowsiness (also first stage of sleep)
Alpha 8 Hz - 14 Hz Relaxed but alert
Beta 14 Hz - 30 Hz Highly alert and focused
The dominant frequency in the EEG pattern determines what shall be called
the current state of the brain. If the amplitude of the alpha range frequencies
is highest, then the brain is said to be in the alpha stage. Note, that
other frequencies still exist and it is impossible to give any "exact
frequency your brain is operating on." However, later references
to the brain states use the simplification of assuming that such a single
Entraining the brain to a desired state
If external stimulus is applied to the brain, it becomes possible to
entrain the brain frequency from one stage to another. For example,
if a person is in beta stage (highly alert) and a stimulus of 10Hz
is applied to his/her brain for some time, the brain frequency is likely
to change towards the applied stimulus. The effect will be relaxing
to the person. This phenomenon is also called the frequency following
When the brain's state is close to the applied stimulus, entrainment
works more efficiently. Thus, when doing a sweep from one frequency to
another, the starting frequency should be as close to your current brain
state as possible. The sweep speed should be such that your brain's state
changes steadily with it, so that the difference never gets very large.
In practice, it is difficult to determine your brain state without extra
equipment (like EEG devices). However, you can quite safely assume that
during the day your brain is in the beta stage (about 20Hz) and you can
start the sweep from there. If you are already somewhat relaxed, you
can use a start frequency of 15Hz or a few Hz lower.
Stimulating the brain with binaural beat frequencies
The easiest way of applying stimulus to the brain is via ears. Other
senses could be used as well, and vision is actually used quite often
(often in addition to hearing). However, humans cannot hear sounds
low enough to be useful for brain stimulation, so special techniques
must be used. One such special technique used is called binaural beats.
If the left ear is presented with a steady tone of 500Hz and the right
ear a steady tone of 510Hz, these two tones combine in the brain. The
difference, 10Hz, is perceived by the brain and is a very effective stimulus
for brainwave entrainment. This 10Hz is formed entirely by the brain.
When using stereo headphones, the left and right sounds do not mix together
until in your brain. The frequency difference, when perceived by the
brain this way, is called a binaural beat.
The effect of the audible frequencies used
To get a stimulus of 10Hz, you may use tones of 500Hz and 510Hz, or 400Hz
and 410Hz, or 800Hz and 810Hz, or so on. The only requirements are
that the tone is heard well enough and that it is below about 1000Hz.
Below 1000Hz, the wavelength of the skull is sufficiently small so
that the sound waves curve around it.
Altered brain states
As mentioned above, applying a stimulus to the brain will eventually
bring the brain's state closer to the stimulus frequency. The following
paragraphs describe some possible effects of this.
Helping in meditation
Meditation is essentially about willingly being able to alter one's brain
frequency to a desired state. While meditators have traditionally used
several years to learn the techniques of meditation, you can now attain
the same effect with brainwave entrainment. No special training or great
discipline is required. Good meditation frequencies are in the alpha
range, from 8Hz to 13Hz.
When a certain brainwave state is experienced and practiced over a period
of time, the brain will "learn" the state change and it will
become easier to self-produce the desired brainwave state at will. Thus,
using brainwave entrainment, you can expect to get some of its effects
later even without any entrainment.
Reducing learning time
The theta stage (4hz - 7Hz) has been found to increase learning capabilities.
In fact, children spend more time in theta stage than adults, which
probably explains the accelerated learning capabilities of children.
Alpha frequencies are also useful for learning purposes. You can play
language cassettes, subliminal tapes, etc. during an entrainment session
for a maximum effect.
Reducing sleep needs
Some people have found that half an hour a day of the Theta stage can
replace up to 4 hours of sleep.
Treatment of certain mental diseases
Brainwave entrainment is used in treatment of depression, low self-esteem,
attention deficit disorder, drug and alcohol addiction and autism, to
name a few.
Brainwave entrainment has also been found helpful in alleviating headaches
Some users have also reported increases in their sex drive as a result
of brainwave entrainment.