What are Brainwaves?
The cells, or neurons, in our brain communicate with each other using electrical activity. This activity is measured in Hertz (Hz). Different states of consciousness are characterised by different levels of dominant electrical activity and can be measured by an EEG machine.

What is Brain Entrainment?

Brain entrainment refers to the brainwave response to recurring sensory stimulation such as pulses of sound or light.

If the brain is given a stimulus of a consistent rhythm, the brain will entrain by synchronising brainwaves to that stimulus. This is called a Frequency-Following Response (FFR).

Just like brainwaves, sound frequencies are also measured in Hertz. If we stimulate the brain with exact frequencies of sound; we can produce a FFR in the brain according to the desired state of consciousness and measure it with an EEG machine.

For example, if we wanted to produce more Alpha brainwaves, one way we could stimulate the brain is with a sound frequency of 10 Hz. However, our ears can only perceive a small range of frequencies. In order to stimulate the brain with such low frequencies, we can use binaural beats.

What are Binaural Beats?

Binaural Beats are a type of brain entrainment, bi meaning two and aural meaning heard.

When two slightly different tones of pure sound are played simultaneously, a pulsing sound is heard. This pulse is called a beat, and the frequency of the beat is equal to the difference between the two original tones.

For example, if one tone is tuned to 440Hz, the other is tuned to 430Hz. The difference between the two tones, or beat, is 10Hz.

440Hz – 430Hz = 10Hz

However, something remarkable happens when the two frequencies are heard in a closed environment, such as stereo headphones. If each tone is presented separately to each ear (one tone in the left headphone and the other in the right), the interaction of the frequencies create a Frequency-Following Response in the brain.

The FFR is processed in the superior olivary nuclei, which are two centres located symmetrically on either side of the brain. These nuclei are the first centres to receive signals from both ears. The information is calculated and then sent to the reticular formation, which is the part of the brain that governs consciousness and awareness. The reticular formation then initiates changes in the thalamus and the cortex, thus changing our state of consciousness.

Therefore, binaural beats help guide the brain into specific and desired states of consciousness.

It is important to note that binaural beats entrain the whole brain, not just the auditory centres of the brain. They also are processed by both hemispheres thus leading to whole brain synchronisation and creating a healthy and optimal functioning brain.

Binaural beats were originally discovered by H. W. Dove, a German experimenter. However, it was after a paper named "Auditory Beats in the Brain" published by Gerald Oster in Scientific American in 1973, that the significance of binaural hearing was realised.

There is a wealth of empirical research into the effects and applications of brain entrainment. For suggested further reading, please see our list here.

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