The sensation of auditory binaural beats occurs when two coherent sounds of nearly similar frequencies are presented one to each ear with stereo headphones or speakers. The brain integrates the two signals; producing a sensation of a third sound called the binaural beat. Binaural beats originate in the brainstem’s superior olivary nucleus, the site of contralateral integration of auditory input. This auditory sensation is neurologically conveyed to the reticular formation and simultaneously volume conducted to the cortex where it can be objectively measured as an EEG frequency-following response. The frequency-following response provides proof that the sensation of binaural beating has a neurological efficacy. (Atwater, 2011)

EEGs presented access to evidence of various levels consciousness.  As the consistent brain patterns of EEGs became apparent, they came to be associated with normal activities. EEGs presented access to evidence of various levels consciousness, named for Greek letters, beginning with alpha.

These associations enabled advances in diagnosis. Although the FFRs elicited by binaural beats appeared at first as the only spikes in an otherwise consistent EEG, gradually in a therapeutic setting, headway was made in the lengthening of these states. Binaural beats came to be seen as a therapy that could play a pivotal role in altering states of consciousness, which led to its use in biofeedback.

This instrumentation is widely availability, although quality equipment is expensive. Open EEG has a do-it-yourself EEG biofeedback training, computer interface device—though like many Source Forge projects, it is not for the faint of heart.