Brainwave Entrainment/Binaural Beats: A Brief Introduction

A brief introduction to binaural beats and brainwave entrainment, and the synchronized brain vs. the unsynchronized brain.

Brainwave entrainment is an effect achieved by listening to two slightly different frequencies of sound in the left ear and the right ear; termed binaural tones. These two similar frequencies are processed by the brain, which in turn creates a third warbling beat, as if the two frequencies merged into one resonating sound within your brain. 

The centre of the brain mainly responsible for this are the superior olivary nucleus, a part of the brain stem. This phenomenon is known as the "frequency following" response and was discovered in 1839 by Prussian physicist Heinrich Wilhelm Dove.

This region of the brain is responsible for perceiving three-dimensional sounds in the environment and their motion through space. What are the implications of this 'phantom tone' generated? It has the ability to render you into an altered state. For instance many use binaural beats as a tool eg. to relax, enhance concentration, induce trance, produce deep meditative states, for lucid dreaming, sleep and as a platform for out of body experiences/'astral projection'.

The following chart shows common frequencies occurring in the brain, coinciding with their respective effects on the mind.  It's important to note here that this is general rule and does not apply for everyone.  For example, in those with a mental illness, such as schizophrenia, it is thought that delta waves are abnormally pervasive during the waking state.


> 40 Hz    Gamma waves    Higher mental activity, perception, problem solving, fear/anxiety

13–40 Hz    Beta waves    Eyes open, active, busy or anxious thinking and active concentration, arousal, cognition

7–13 Hz    Alpha waves    Eyes closed, relaxation (while awake), borderline-sleep and pre-wake, drowsiness, meditative states, lucid dreaming

4–7 Hz    Theta waves    Dreaming, deep meditation, Rapid eye movement (REM) sleep

< 4 Hz     Delta waves    Deep dreamless sleep, loss of body awareness


The Unsynchronized and Synchronized Brain

In a brain not subjected to binaural beats in normal waking state, the data from an EEG would reveal the predominant frequencies in the brain to be in the 13-30Hz range (beta waves). The left and right hemispheres would not be synchronized so one side may have more or less than the other. Of course beta waves would not be the only waves in the brain, simply the most dominant as we all have varying volumes of other waves including a few delta, some theta, some alpha as well as gamma in our waking state.

But it's noteworthy that the dominant waves (in this case the beta waves) have the most influence overall on your mental state than any other; just like music played would lessen the perception of a loud fan, so would the predominant waves in your brain 'drown out' the other frequencies to some degree.

Of course if you were in a deep sleep or in REM the reverse would occur, as 1-7Hz take predominance (delta and theta waves) and the higher frequencies become less and less prominent with beta/gamma waves becoming more or less absent. The left and right hemispheres of the brain would be uneven, just like in the beta wave example.

Visualise the unsynchronized brainwave model as an abacus, each bead representing a quantity of a wave, each rack of wood signifying a wave from gammas all the way down to the deltas.  The beads are in a constant state of flux: being pushed back and forth, disregarded entirely or unevenly distributed to the left and right sides.  The synchronized brain, in contrast, would be mostly even in the quantity of waves on either side of the left and right hemispheres and in the average person would be dominated by beta/alpha waves in an alert waking state.

By synchronizing both hemispheres, they function in synergy rather than one dominating the other; thereby reducing the power struggle and increasing the efficiency of the brain.  Binaural beats aren’t the only means of achieving synchronicity between hemispheres, in fact rhythmic sounds such as drum beats or music may achieve the same ends, although you would not be able to program which frequency your brain would follow.