This is a question I have noticed to concern many people, who are researching the issue. I have come across this question in forums, Yahoo Answers, in blogs, and all other sorts of  places. I can definitely empathize with someone who is looking to find a solution to a problem like anxiety, migraine, pain, etc., and needs reassurance and scientific proof that brainwave entrainment actually works!
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.
You also may find that after pushing yourself really hard, now you have pushed yourself a little too much, and you’re getting into overwhelm. You may want to ride that overwhelm like a wave to where it’s pushing you just a little bit, but not so much that it will push you over the edge and have you take a dive. So, maybe on Saturday, after pushing hard all week, you might decide to put on the releasing tracks. In this way, you can still experience a very deep and blissful meditation, but without all the push from the carrier frequencies and the biofield amplitude.
Participants in the included studies were children and adults, either healthy or with conditions such as learning disabilities, attention deficit hyperactivity disorder, migraine, stress, anxiety and myofascial pain. Interventions included single, alternating, ascending or descending frequencies of photic or auditory stimulation or audiovisual entrainment selected either by the participant or by the investigator. Nearly half the studies used single sessions and the rest used multiple sessions ranging from nine to 100. Length of session varied from 0.5 seconds to 60 minutes. Frequency of session varied from twice daily to weekly. Outcomes reported in the review included cognition (including verbal skills, performance skills, attention, memory and overall intelligence/achievement), short- and long-term stress, pain, headache/migraine, mood, behavioural problems and premenstrual syndrome (PMS).
Although the binaural beats / music / downloads on this site contribute to wellness, they are not intended as a replacement for medical or psychological treatment. No medical claims are intended express or implied. Despite the fact that all statement made on this website are supported by research, no statements have been evaluated or approved by the U.S. Food and Drug Administration or any other international governance responsible for health care.
Sensorimotor rhythm (SMR) is one final type of brainwave that has been studied. SMR, also known as low beta, is a type of brainwave, which occurs in the sensorimotor cortex, in the 12 to 15 hertz range when that area of the sensorimotor cortex is idle and immobile. The purpose of SMR brainwaves is not well understood, but some neurofeedback practitioners report training to increase SMR brainwaves can be beneficial for people with autism, epilepsy, ADD, insomnia, drug addiction, and as an aide to better manage stress.
Generally, the established brain entrainment technology has been to use various static levels, lowering the carrier frequency of the binaural signals over time. By doing this, you basically increase the resonant power of the carrier frequency to resonate more deeply with the resonant frequency of the brain and the nervous system. This process pushes the nervous system over time. The limitation I find with this system is that it takes a static approach, in the sense that it gives the nervous system the same degree of stimulation day in and day out. The idea here is that if you keep whamming your nervous system with the same stimulation on a daily basis, it will eventually kick in and learn. Then your nervous system and your brain will jump to the next level.
The reason I am telling you this is to consider that it is critical for you to seek advice from sources that have wide-spreading experience with brainwave entrainment. Having personally used the technology for over 13 years, in combination with many other more ‘traditional’ methods such as yoga, meditation, visualizations, positive affirmations, NLP, etc., I believe that my personal experiences and the in-depth research I have conducted in order to make sure I approach this safely, can serve as a good starting point for you.
I was not looking forward to returning back to my house as I live on my own so was very pleased to see that the “equisync” CDs had arrived in my absence. Ever since I have been back I put a CD on each evening and the change has been totally fantastic. The meditation is unbelievably calming and soothing, the inner-voice has been silenced and quite often I just put it on to drop off to sleep with the sound of gently falling rain. I can feel each day starting calmly and things like organising the memorial service have not been the strain and upset I would normally have expected. I could wax lyrical for hours because the benefits are truly and utterly fantastic. Never did I think I would find anything that would lift my spirits, clear my mind, calm the inner space but Equi-Sync has done that, and more.
This music encourages a state of delta relaxation. Delta brainwaves are most prevalent during deep, dreamless sleep. The delta state is a mostly unconscious state that is essential to one’s physical, emotional, psychological and spiritual wellbeing. People who are able to achieve a state of delta relaxation through meditation will sometimes describe spiritual encounters and out of body experiences. The delta state is perfect for inducing profound spiritual experiences, healing and deep subconscious repatterning. Delta frequency brainwave entrainment music is also a fantastic cure for insomnia.

Heart rate variability: A new study suggests that among those with low HRV (heart-rate variability), brainwave entrainment can increase HRV. Researchers studied individuals ages 20 to 70 and administered alpha brain stimulation. The alpha wave stimulation resulted in greater heart-rate variability. Since a low HRV is associated with early mortality and poor psychological and physical health, efforts made to increase it should be regarded as beneficial.
Admitted, I haven’t listened to all the tracks yet, but while listening to the demo alone over the course of a month-and-a-half I, too, had a transcendental experience that was amazing! So I determined pretty quickly to save the money and buy your product, even though I really can’t afford it. Yes, over the last 3 years meditation has become that important to me.

Binaural Beats or “binaural tones” are created by playing slightly different frequencies separately into each ear. The difference between the two frequencies stimulates a response in the brain which correlates with this frequency difference. For example, if we present a 100 Hz tone to the left ear and a 105 Hz tone to the right ear, a frequency of 5 Hz is stimulated. This is what is known as the “frequency following response”.

In the past few issues of the Advocate Voice Newsletter and the Fibromyalgia & Chronic Pain LIFE magazine, we have offered ideas about  several forms of cognitive behavior and mindfulness information.  In the chronic pain community these techniques combined with other therapies, including medications and alternative modalities, can help people sleep, function, relieve stress from pain and improve their quality of life.  This month’s app, Brain Wave, 30 Binaural Programs, is another tool to help introduce the idea of using your mind to help control pain and relieve stress.
In all professionally produced meditation programs, you train your brain gradually. That is how you successfully develop. Just like training the body, you progress gradually. This is the key. In BrainAscend you start with level 1. Each track is 30 minutes.  Use it once per day for 30 or 60 minutes at a time (once or twice in a row. Use repeat/loop function in your player) or twice per day for 30 minutes at a time. You should use every level for at least 2-3 months before moving to the next. The exception is level 1 which is an introductory level which you can use for a week or so. After that time, if you can repeatedly remain fully aware on your current level without falling asleep (even if playing it twice in a row) you can move on to the next level. Until then you should continue on your current level. Listen with closed eyes, either sitting up or laying down.
However, if you are looking to do something more practical, like improve your mental sharpness, overcome attention issues, succeed at work, be more productive, you may want audios that target more of the alpha and beta ranges, and are created to put you in peak performance states of mind. In this case, a program like our Effortless Overachiever Bundle would be much more practical and helpful for you.
  It's like gaining a new level of clarity... understanding.... wisdom. When you're able to artistically and logically render solutions to problems... when you can objectively and subjectively evaluate opportunities and their innate qualities... when you can read people and empathetically understand them... you're given a foresight that others simply lack.

Because the brain filters and interprets reality in a split-brained way, we tend to see things as separate and opposed, rather than as connected and part of the oneness spoken of by the great spiritual teachers (and, in the last few decades, by quantum mechanical physicists). Thus, at a deep level, the dual structure of our brain, in conjunction with brain lateralization, predisposes us to see and experience ourselves as separate from, and often in opposition to, the rest of the world—instead of experiencing the elegant interconnectedness between us and everything else. Our childhood associations and programming build on this inborn tendency by training us to seek this and avoid that, to move toward pleasure and away from pain, to do good and not bad, and so on. The greater the lateralization in the brain, the greater the feelings of separation—and the greater the feelings of separation, the greater the fear, stress, anxiety, and isolation.
Leap over obstacles and hurdles, easily – Nothing worth having is ever easy. Everyone faces problems. The difference is, how you handle those problems. Imagine if you never even see them as problems to begin with... if it's just easy, somehow, to envisage simple solutions to hurdles and enjoy the challenge. Successful people thrive on challenges... you could begin to experience the very same rush!

Much of what is currently written about brainwave entrainment, especially on the internet, is simply … incorrect.  It seems par for the course that when something of huge value is discovered as a potential ‘internet product’ that it is going to be marketed within an inch of it’s life. And often with less than stellar regard for actual science, research, or factual knowledge. 
I’ll give you another relevant analogy.  When you are bodybuilding, working hard to build strength and build your muscles, you can push yourself to the point that we know is healthy.  But what happens if you try to max out with the same exercise past the point that we know your body can handle?  You’re going to get hurt, and you’re not going to get buff any faster.  You can’t just push yourself to the limit with the barbell as many times as you want in a day/week.

Neural oscillations are rhythmic or repetitive electrochemical activity in the brain and central nervous system. Such oscillations can be characterized by their frequency, amplitude and phase. Neural tissue can generate oscillatory activity driven by mechanisms within individual neurons, as well as by interactions between them. They may also adjust frequency to synchronize with the periodic vibration of external acoustic or visual stimuli.[3]