It is generally agreed by scientists that the brain oscillates at various rhythmic frequencies that are divided into 4 main bands, connected to 4 different modes of mental activity.
All these bandwidths are active all the time, but the strength of the waves varies with the mode of activity.
From this, researchers have theorised that by presenting an external pulse stimulation at a certain frequency we can boost the strength of those frequencies in the brain.
Thus by sending an Alpha Pulse at, say, 10hz we can stimulate Alpha Waves and thus an Alpha state of mind - ie. a creative dream-like state.
In the 70s this was called "Biofeedback".
This is the basis if the "Brain Machine".
Have you ever thought why techno, which is often hard and aggressive, has a dreamlike, trancelike quality? This must be partly because the 16th note pulsations of hi-hats or sequencers are all in the Alpha pulse band.