Your brainwaves get manipulated daily, hourly, continously, whether you are aware of it or not.
Decades of studies published about binaurals show that the soundwaves can clearly induce certain pre-dominant patterns.
How useful it is, (and how much of your own subconscious you wish to confront) really would depend on your own expectations, I suppose. There is no free lunch, and if this stuff works as advertised, you will have to deal with suppressed emotions and memories, as well as sometimes painful new insights about yourself, your motivations and your life decisions.
As for me, my few years of Holosync has exceeding any expectation I could have had for it.
