Binaural Beats
Binaural beats are brainstem responses to the interaction of two different frequencies heard in either ear. (The Monroe Institute, 2004)
Binaural beats and brainwave entrainment is becoming a booming industry. Two years ago when I first started looking into the phenomenon, I struggled to find information, but now, the amount of info available on the web is amazing. Every day there are new resources both free and for sale on how to use and make these perceived sounds. What it all boils down to is using simple sine waves of different frequencies in the left and right ear (usually through stereo headphones) to create a separate frequency of the difference between the two frequencies. When using these frequencies for brainwave entrainment it is best to keep the difference or binaural beat within the frequencies of desired brain function.
There are four basic frequency groups to shoot for when using binaural beats for altered consciousness.
.5Hz - 4Hz (Delta) is considered to be a state of deep relaxation or sleep. It is also considered regenerative and the range for transendental meditation
4Hz - 8Hz (Theta) is considered to be a state of drowsiness and also the range for trance and intuitive states of consciousness
8Hz - 14Hz (Alpha)is considered to be a relaxed, but alert state and can be good for light meditation
14Hz - 30Hz (Beta)is considered to be a highly alert and focused state. Most awake and functionaing at a high level (multi-tasking)happens in the range of 16-20Hz