What are Binaural Beats?
Before I can get into what binaural beats are, let’s talk about sound.
Sound occurs as waves. When sound waves reach the ear, the eardrum vibrates and the vibrations are decoded as sound by the brain. A sound wave has peaks and valleys, just like a ripple of water. The number of peaks and valleys that occur in the sound wave per second is referred to as the frequency and is measured in Hz (Hertz).
The greater the frequency (more peaks and valleys per second), the higher the sound. A whistle, for example, would have a high frequency. Deep bass would have a very low sound frequency.
Binaural Beats is the perception of a subtle beating or pulse sound when both ears are exposed to two different audio tones at minimally differing frequencies, over headphones. The Beat refers to the subsonic frequency difference between the tone in the left ear and the tone in the right ear. For example, if the left ear is exposed to 120Hz and the right ear is exposed to 110Hz, the Beat frequency is 10Hz. By subsonic, I mean that this 10Hz frequency would otherwise be completely imperceptible as a sound on its own.
How do Binaural Beats affect brain activity?
Brain activity can be measured electrically, via EEG (Electroencephalography), also as waves. The more active the brain, the higher the brainwave frequency. If very alert, for example, you would be in a high brainwave frequency state. If sleeping or in deep relaxation, your brainwave frequency would be quite low.
Introducing Brainwave Entrainment
Brainwave Entrainment (sometimes called brainwave synchronization), is attempting to intentionally cause brainwaves to move to a specific frequency. This is purportedly possible by exposing the sensory system to an external stimulus such as sound. Unfortunately, sound operating at frequencies in a range similar to that of brainwaves would not be perceptible to human hearing. But we can, instead, take advantage of the binaural beats phenomenon.
Alter your State of Mind
The purpose of attempting brainwave entrainment is to bring one’s conscious into a preferred state. For example, during deep meditation, an individual may want their mind to be optimally primed for relaxation. By exposing the auditory cortex to binaural beats at the proper frequencies (delta range), one can potentially move their brainwaves to fall in sync and assist bringing the mind into a relaxed state. Similarly, a student wishing to focus on finishing some homework may wish to expose themselves to a stimulus in the gamma frequency range, eliciting a brainwave synchronization response, assisting their effort to focus on the task at hand.
Various named frequency ranges occur when the brain is in certain states. The following table shows these ranges and what mental states they typically indicate.