Some people believe that using this stuff can be a replacement for meditation. While sitting passively and listening to something that can give you the same effect frequency-wise as meditation, there is still far more benefit to meditating than just entrainment. Meditation and mindfulness allow you to really understand yourself on a level far deeper than technology will bring you.

Brain waves are electrical activity patterns caused by the neurons of the brain communicating with each other. Brain waves can be detected using sensitive medical equipment such as an electroencephalogram (EEG) monitor. Brain waves provide an indication of the mental state of an individual. In other words, the appearance of brain waves is directly connected to what a person is doing, thinking or feeling. The different Brain states are: Gamma, Beta, Alpha, Theta, Delta. You have your own unique brain wave patterns that function habitually. Some of these brain wave habits are useful, and others need some fine-tuning. When your brain is functioning efficiently, your brain waves are “in sync” with your activity, but stress or lack of sleep can interfere with this natural harmonious relationship. To restore this harmony, at Gaia Meditation, we have developed a wide range of free audio programs, including meditation music, relaxation music, sleep music and plenty other Sound Healing programs.

OK – so some of this is pretty common marketing hype. Consumers have become almost numb to such hyperbole. But still we see some of the common – almost ubiquitous – elements of pseudoscientific scams. The company claims that the device is “effort-free”, that the results are “rapid and long-lasting,” that it is the “most effective” method of its kind, and that it is useful for a broad range of applications (hey, why limit the market). I am used to such hype about dishwashing detergent, but find it intolerable when applied to a pseudoscientific device with medical applications.
Stressed out after work? Need to relax and be focused before a test, exam, or interview?. This CD is for you. Wish I could explain how this CD works on your brain's "entrainment" but they do enclose a benefits description inside the CD case. It's amazing to listen to and see/feel the results after hearing the entire CD with a quality set of headphones on. Note: also works well with earbuds. I couldn't tell if the last track had played or not on the Nexus just takes you away then brings you back ... into something more structured and coherent.
It’s important to keep in mind; a person’s own experiences will be somewhat relative to their starting point. If you are a person who is completely stressed out, burned out, hanging on the ragged edge, experiencing total adrenal fatigue, and you’ve been at that point for awhile, then to you even a small degree of mental quiet and physical relaxation that meditation and brainwave entrainment bring will feel like a tsunami of relief.
If you happen to be someone who already knows about the physics of sound, then you’ll know that frequencies of 20 hertz or less cannot be heard by the human ear. So how on earth can we use sound to create frequencies as low as 0.1 hertz, and how will you be able to hear them? This is where the “magic” of binaural beats comes into action. Actually, it’s not magic at’s more physics! If you are feeling a bit adventurous, then click on the following link to find out how binaural frequencies are created.
A warning: Be sure to listen to these two tracks no more than twice each per day. Any more and your beta-thought centers can have TOO much energy in them, causing you to feel like you are on a stimulant. Some people may only be able to listen to each track once per day without feeling over-stimulated. That's fine, just go with what works for you. Sometimes less is more when it comes to brainwave entrainment. Don't push too hard trying to force-grow your brain cells. :-)
People who meditate regularly enjoy many benefits such as increased sense of well being, happiness, contentment, and far less anxiety that many other people. Some believe that this is due to both hemispheres of the brain being in sync with each other, which meditative practice can provide. Therefore, a goal of using technology to entrain the brain and align the frequencies of the brain hemispheres has become a very interesting avenue of science and experimentation.

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]