While a practical understanding of brainwaves has been around for as long as people have been singing, chanting, and drumming, a scientific view of the electrical activity inside the human brain was not published until 1924 when German psychiatrist Hans Berger developed a machine for sensing and recording activity in the brain by attaching small electrical sensors to the scalp of his patients and recording the resulting electrical activity. Berger’s inventions and discoveries were built upon the earlier work of Richard Caton who published animal studies on brainwave oscillations in 1875.
There appeared to be some evidence that 10 Hz stimulation (alpha waves) improved anxiety, but it wasn’t statistically significant. A study that utilized a ramping format of alpha to theta to delta waves (over the course of 10 minutes) found a significant improvement in anxiety. In terms of long-term stress, there is evidence that alpha and beta stimulation improved measures of “competence” and “emotional exhaustion.”
There basically are a few things that you can use to deduce whether you think these claims are true, and will work for you.  A few manufacturers of this type of product have taken the time to hook up experienced meditators (like zen monks) to encephelographs, then fashion their audios to mimic what is occurring in these deep meditators’ brains.  It would make sense then, to a large degree, that you could experience similar benefits from your brain undergoing this process. 
Alpha brainwaves are resonating just below beta brainwaves at the frequency range of 8Hz to 12Hz on an EEG. Beta brainwaves are the normal, waking life, active, rational thinking and problem solving brainwaves that are dominant in most people throughout the day. Alpha brainwaves begin to show up when relaxation occurs. Often times the simple act of closing your eyes can product spurts of alpha waves. Taking a few deep breaths or consciously relaxing will do the same. When alpha waves become dominant, the body and mind are usually comfortably relaxed.

Entrainment is a phenomenon seen is a wide variety of different natural circumstance. In the field of chronobiology, the study of biological rhythms in living organisms, entrainment is the synchronization of a circadian rhythm with the rhythm of an external pattern, such as the synchronizing of women’s menstrual cycles with the phases of the moon or with one another in a group.
I just wanted to thank you guys for having such an outstanding product available. I used to meditate when I was younger but got away from it over the last 7-8 years. I had difficulty starting back up, but since I started using your cds I have no difficulties getting back into it; and am now meditating 2 hours per day and have never felt better. I have only been using them for a couple weeks but have already noticed a difference. Thanks again for creating such a wonderful product and I will be sure to recommend it to everyone.

Brainwaves, or neural oscillations, share the fundamental constituents with acoustic and optical waves, including frequency, amplitude and periodicity. Consequently, Huygens' discovery precipitated inquiry[citation needed] into whether or not the synchronous electrical activity of cortical neural ensembles might not only alter in response to external acoustic or optical stimuli but also entrain or synchronize their frequency to that of a specific stimulus.[16][17][18][19]