About binaural beats:

If each of our ears hears different single tone frequencies, our brain tunes in to the difference of the two frequencies and generates brain waves correspondingly. For example if your left ear, hears a tone with a frequency of 200hz or 200 cycles per second and your right ear hears a tone of 203hz, your brain generates a brain wave pattern equivalent to the difference of 200hz and 203hz which is 3hz or 3 cycles per second.

About brain waves:

Our brain generates different brain wave patterns depending on our activity. Brain waves during waking are different from the brain waves when you are sleeping, in a sports activity or daydreaming. Different cycles or stages of sleep also have different brain wave patterns.

Binaural beats – brain wave entrainment:

Medical scientists have used binaural beats to help people with regards to improving health and treating ailments with psychological related conditions. Patients are ‘doses’ of binaural beats using headphones and targeting brain wave patterns designed for the specific condition.

via How to Boost Binaural Beats Power | Brain Entrainment.

Brainwave entrainment is the use of some external stimulus, usually different sounds that a person will hear with stereo headphones, to induce a certain level of brain wave activity. When a person’s brainwave activity is artificially altered by these means, it will subtly shift their awareness and perception.

Using binaural beats is a common and effective method of brainwave entrainment. In order for the binaural beats to be effective, a person must be using stereo headphones so that they can hear a different sound in each ear.

Most of the time, the binaural beats will be embedded underneath the layers of tracks on a song, usually soothing ambient music or soundscapes, so that the person listening can focus on the music and not on the frequencies they are hearing. If you either find or create effective binaural beat audios to listen to in stereo heaphones, the frequencies should blend perfectly into the background, and you should not be able to consciously notice them unless you really try to isolate them.

via Self Improvement And Motivation: Increase Creativity and Redce Stess Using Alpha Meditation.