Brainwave entrainment was first discovered in 1839 by the German experimenter H. W. Dove. Mr. Dove found that, just as AM frequencies are able to curve around the earth and around mountains, low frequencies (<1000 Hz) are able to actually curve around the curvature of the human skull. This appears to be an evolutionary adaptation of certain species. This phenomenon can be utilized when either ear is exposed to a different frequency. If the left ear is given a 400 Hz "tone" and the right ear is exposed to a 410 Hz "tone", the brain perceives a third wave that has a frequency of 10 Hz. When exposed to this frequency, the brain's own wave slowly comes into tune with this third tone (mindmatter.com). This entrainment of the brain's waves will yield one of four (or five depending on the source) different frequency subsets. These sets are alpha, beta, delta and theta (gamma is included in some studies but not all) (www.bwgen.com). Each of these subsets is thought to produce a different mindset or mood. Starting with the lowest frequency; delta is thought to induce the sleep state.

The delta frequency is thought to lie between 0.5 Hz and 4 Hz. Other states linked to the delta frequency include release of growth hormones from the pituitary gland, self-healing and dreamless traces. The next frequency is theta, which exists from 4-8Hz. This state/ frequency is associated with learning. It is thought that, when the brain is exposed to this "beat wave" (another commonly used term for entrainment), that one would be able to learn more rapidly, recall things more readily and increased activity. The next area is the alpha frequency. This beat wave lies between 8 Hz and 14 Hz. This state is associated with euphoria and happiness. In this state, the subject is non-drowsy...