What is Brainwave Entrainment?
Brainwave entrainment refers to the brain’s electrical response to rhythmic sensory stimulation, such as pulses of sound or light.
When the brain is given a stimulus, through the ears, eyes or other senses, it emits an electrical charge in response, called a cortical evoked response (shown below). These electrical responses travel through the brain to become what you “see and hear.”
Scientists measure this activity using sensitive electrodes attached to the scalp.
When the brain is presented with a rhythmic stimulus, such as a drum beat, for example, the rhythm is reproduced in the brain in the form of these electrical impulses. If the rhythm becomes fast and consistent enough, it can start to resemble the natural internal rhythms of the brain, called brainwaves. When this happens, the brain responds by synchronizing its own electric cycles to the same rhythm. This is commonly called the frequency following response (or FFR).
FFR can be useful because brainwaves are related to mental state. For example, a 4 Hz brainwave is associated with sleep, so a 4 Hz sound pattern would help reproduce the sleep state in your brain. The same concept can be applied to other mental states, including concentration, relaxation and many more.
If you listen closely to most sessions, you will hear small, rapid pulses of sound. These pulses may be harder to detect if you turn off tones, but noise and background sounds are also embedded within them. As the session progresses, the frequency rate of these pulses is changed slowly, thereby changing your brainwave patterns and guiding your mind to various useful mental states.
Brainwave entrainment has over 80 years of research behind it.
What is Entrainment?
Entrainment is a principle of physics. It is defined as the synchronization of two or more rhythmic cycles. The principles of entrainment are universal, appearing in chemistry, neurology, biology, pharmacology, medicine, astronomy and more.
CASE IN POINT: While working on the design of the pendulum clock in 1656, Dutch scientist Christian Huygens found that if he placed two unsynchronized clocks side by side on a wall, they would slowly synchronize to each other. In fact, the synchronization was so precise not even mechanical intervention could calibrate them more accurately.
A clock is a simple example of a system responding to entrainment, but the same effect can be seen in more complex systems such as the brain.