The brain emits an electrical charge between its cells, the neurons, in response to an outward stimulus of the senses, whether the ears, eyes, or other senses. The response is called a cortical evoked response. The electrical bursts throughout your brain determine how, and what, you see and hear. These electrical bursts can be measured by connecting electrodes to the scalp.

If the stimulus is rhythmic, such as music, the rhythm is produced in the brain as electrical impulses. If the rhythm becomes consistent and fast enough it resembles the natural brainwaves. The brain then responds by synchronizing its own pulses to the beat of the music. This response is called Frequency Following Response. This frequency following response appears in chemistry, neurology, astronomy, pharmacology, and biology.

For example in 1656, a Dutch scientist named Christian Huygens, was working on the design of the pendulum clock. He found that if he put two unsynchronized clocks side by side they would slowly synchronize to each other.

Another example is that if a tuning fork which produces a frequency of 500 Hz is struck causing it to vibrate if it is brought near another 500Hz tuning fork, the second fork will begin to vibrate as well. The first fork is said to have entrained the second fork.

While the discovery of brainwaves may be recent, brain entrainment has gone on socially for ages by tribal chanting, drum beats, and dancing.

Intentionally changing the level of brainwaves through entrainment has a number of benefits. If a person has sleeping disorders, entraining their brain to the Theta stage leads to relaxation. People who have attention deficit disorder can benefit by reaching the Beta stage. A state of mediation can be attained more quickly if the brain is entrained to the Alpha state. The Alpha state is very receptive to learning. When a subject is successfully hypnotized they usually are in the Alpha state. Breaking bad habits and starting new habits in their place will be more successful if the Alpha state is used to promote the new habit.