Abyssal Brain Stimulator use audio and video stimulus. The humans cannot hear sound low enough to be useful for brain stimulation, so we've used a technique called binaural beats. In the left ear is presented with a steady tone of 400Hz, and the right a steady tone of 410Hz, these two tones combine in the brain. The 10Hz diffrence is perceived by the brain. This 10Hz is formed entirely by the brain.