delta (0.5- 3.5 Hz.) generally found in sleep states. theta ( 4- 7 Hz.) a hypnogogic state. alpha ( 8-13 Hz.) relaxed, alert state. beta ( 14-30 Hz.) states of agitation or intense mental concentration.
A suitably-entrained brain is much more responsive to suggestion, and is even likely to experience vivid hallucinations. This is used in TeleVision Programming to, well, Program the Sheeple.
The hemi-synch, and related mind-machines, can produce alpha or theta waves, on demand, according to the operator's choice.