From Wikipedia
http://en.wikipedia.org/wiki/Binaural_beats#searchInput
Binaural beats or
binaural tones are
auditory processing artifacts, that is apparent sounds, the
perception of which arises in the brain independent of physical
stimuli. This effect was discovered in 1839 by
Heinrich Wilhelm Dove.
In nature, two sounds that are similar but slightly shifted in
frequency will
beat to produce two new frequencies which are the
sum and the
difference of the original two sounds. For example, a 400
Hz tone and a 410 Hz tone will form a ~405 Hz tone pulsating 10 times per second.
The brain produces a similar phenomenon internally, resulting in low-frequency pulsations in the
loudness of a perceived sound when two tones at slightly different frequencies are presented separately, one to each of a subject's ears, using stereo
headphones. A beating tone will be perceived, as if the two tones mixed naturally, out of the brain. The frequency of the tones must be below about 1,000 to 1,500
hertz for the beating to be heard. The difference between the two frequencies must be small (below about 30 Hz) for the effect to occur; otherwise the two tones will be heard separately and no beat will be perceived.
Interest in binaural beats can be classified into two categories. First, they are of interest to
neurophysiologists investigating the
sense of hearing. Second, some
protoscientists believe that binaural beats may influence the brain in more subtle ways through the
entrainment of
brainwaves and can be used to produce relaxation and other health benefits.
OR, you can just crank up the rock and roll, and headbang!
