:-) Doesn't matter which ear, but you have to be using stereo headphones. Basically, (as I understand it, not an expert) you are trying to get your brain to resonate a particular natural frequency. This is hard for us to do because of all the electropullution and RF crap bombarding us.
So if 200 htz plays in one ear, and 207 htz in the other, the brain will compensate by resonating 7 htz (I think this is earth's resonance?) or whatever frequency you're trying to achieve.
The science looks reasonable to me, and I've already stated that I had an immediate response to some of the tunes.
Some didn't do anything and some were absolutely unbearable.