The four major brainwave cycles measured are
- Delta - 1-4 cycles per second (deep sleep).
- Theta 4-8 (hypnagogic state)
- Alpha x8-13 (altered states of consciousness/meditation)
- Beta 13-26 (mental concentration/also stress, anxiety).
If you want a natural effect listen to polyrhythms: drum circles, African rhythms, Tibetan and Moroccan music. The chaotic quality of the shifting natural patterns confuses the brain - as it tries to find the "correct" timing - we decipher our own "beat" within it, the action of doing this forms the non-fucsed, attentive mental state which stimulates Alpha wave activity.
The other "turn-on" with sound is frequency. This is where the "chakra" idea comes into it. Bass most strongly affects the lower nerve centers - sexual organs and the stomach. Midrange affects the chest - particularly the heart rate - fastert kick drums can affect the heart and thus manipulate adrenaline levels. Top end and white noise has most effect on the head/brain - as do piercing acid squeals. And the rest of it - melody, chord progressions, scales, the human voice? These are what influence our more subtle emotional responses which we are highly varied. To mis-quote Terence McKenna, "we have more words to describe narcotics than we do our emotions", and they seem to be one of the key areas of development of our species.
Any move to a permanent higher consciousness would require greater emotional capacity and understanding of inner rhythms via biofeedback techniques. These techniques enable conscious manipulation of brainwave and body function. This is why people are exploring group trance states in time and space at this period in human evolution."