Entrainment
From Organic Design wiki
Binaural beats
Brainwave synchronization (Wikipedia:entrainment) may be achieved when audio signals are introduced to the brain causing a response directly related to the Wikipedia:frequency of the signal introduced, called binaural beats. Two tones close in frequency generate a Wikipedia:beat frequency at the difference of the frequencies, which is generally Wikipedia:subsonic. For example, a 500 Hz tone and 510 Hz tone will produce a subsonic 10 Hz tone, roughly in the middle of the alpha range. The resulting subsonic tone may affect the state of Wikipedia:mind of the subject.
