I used to produce CDs of this stuff for a meditation company. Typically you won't get any benefit from it unless you're prepared to spend at least 40-70 minutes at a time, in complete relaxation. So using it while doing something else, for example while riding the tube, is pointless because your brain is alert to other stimulus and never syncs.
So you need to close your eyes, or wear an eye mask, and chill in a comfy chair, or lie down.
You will not hear the effect using speakers. Or rather, you may hear something but you won't get the benefit unless you use stereo headphones.
This is how it works. The frequencies we want are alpha waves, in the low 2-4hz range. Now, no speaker in the world can play bass that low without blowing out the cone. So instead, we create a phase offset of 2-4hz that your brain picks up, even though it isn't really hearing it.
To achieve this, we play a low 100hz tone through your left ear, and (for a 4hz effect) a 104hz tone through your right. When you listen on stereo headphones, the effect is more percieved than heard. It's like a subtle "whooshing" around your head, bit like a very soft helicopter. whup-whup-whup-whup sort of thing.
Now, it takes your brain 10-20 minutes just to get in sync. So when we design these, we actually begin with a much faster tone of around 20Hz and gradually take you down, over the course of 20mins. Once you're down, we typically add an 8hz spike every 10-15 mins, just to keep you lucid. And then we bring it gradually back up at the end.
There is a lot of research available into what exposure to prolonged sessions of various frequencies will do. There is documented evidence to suggest that certain frequencies will improve your concentration, make you smarter (remember stuff better), and others can relax you, or refresh you. Some frequencies can even be used as sleep replacers - when you have 60 mins in hand but need the benefit of a full night's sleep.
There is also, on the fringes of research, some anecdotal evidence to suggest that exposure to certain frequencies may improve ESP in those who already manifest it. Can't comment on that. I tried juicing myself on ESP vibes and I still haven't managed to pick the winning lotto numbers yet.
