In 1990, American psychologist Dr. Thomas Budzynski published a research paper where low frequency waves (0.5Hz to 30Hz) were shown to reliably affect behaviour and mental state. When brainwaves are measured on the surface of the scalp, they can be categorised based on their frequency and amplitudes. These categories correspond to specific states of excitement or cortical arousal.
In 1991, Dr. Dale Foster presented reliable data and references showing that sound waves alone are sufficient to produce EEG entrainment. When manipulating alpha EEG, Foster specifically distinguishes between the use of biofeedback and binaural beats. A significant amount of research and documentation already exists regarding binaural beats, however Foster noted that consciousness management via the use of binaural beat stimulation has only received the attention of a small minority of researchers.
A binaural beat is created by outputting two different frequencies, one into each ear. As a result, a third tone can be heard, which is based on the difference in frequency of the other two tones. For example, a 200Hz tone in one ear and a 210Hz tone in the other produces a 10Hz “beat” tone. According to Foster, this is produced by “an auditory brainstem response which originates in the superior olivary nucleus of each hemisphere. The beat results from the interaction of two afferent auditoxy impulses, originating in opposite ears, below 1000 Hz; and which differ in frequency between one and 30 Hz.” As the two waveforms flow in and out of phase within the superior olivary nuclei, the result is a different third tone.