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!
Brain Sync Brainwave Technology is the simplest, most affordable way to directly tap into your higher potential and unleash your power to think, create, heal and to change. There’s no training necessary, no need to travel anywhere, or spend hundreds of dollars on complicated home training programs that take up a lot of your valuable time. Just 30 minutes a day will bring outstanding results. When your brain is in balance your ability to think, learn, create and recall is remarkably enhanced. Perception expands, memory improves and you can concentrate more easily. You sleep better and are more resiliant to stress. A balanced brain brings freedom from fear, worry and even addictions that have stood in the way of you experiencing more fullfillment and joy.
Brainwave Entrainment is the process of synchronizing the brain to specific frequencies and patterns embedded in audio tracks. These frequencies correlate to specific emotions, feelings, and even energy levels. Using nothing more than sound, Brainwave Entrainment can enhance creativity, change moods, and even alter behavior like sleep and energy levels.
They are a useful and effective tool that allow you a structured means in which to entrain your brain into a desired, new brainwave state using an intended set frequency range of the audio track. Frequency ranges for desired sleep, recovery and deep meditation states to different/higher frequency ranges for performance “flow-states” and high-level focus and calculation.

Another study found slight improvements in trait anxiety as a result of entrainment. It was noted that the study with the most successful protocol started at 30 Hz beta and ramped the frequency down until the person experienced relaxation for 15 minutes. This was then followed with a session of 8 Hz to 14 Hz for 7 minutes. The results suggested that 75% of individuals improved on their measures of long-term stress.
Are you someone who has turned to meditation or yoga as a way of relieving stress and improving your overall well-being? Yoga and meditation are time-proven methods, used for centuries, which restore mental, physical, and spiritual balance in people’s lives, and brainwave entrainment can be used in conjunction with these practices for even deeper levels of benefit. 
“A light sound machine is a brainwave entrainment tool.  Using sound (headphones) & light (strobe light goggles) stimulation, listeners are gently guided into specific brainwave states. Each audio beat and pulse is a specific frequency. Our minds ‘think’ in terms of frequency. Brainwaves change frequencies based on neural activity within the brain. Hearing and vision are considered the favorable senses for affecting brainwaves safely. By presenting beats and pulses to the brain, the brain begins to mimic or follow the same frequencies. This process is referred to as entrainment. In essence, these instruments speak to the mind in it’s own language – the language of frequency.”
Want to use it as a serious tool for self-development, long-term meditation support, etc.? Find a supplier that is in alignment with your own values and knows what they are doing. E.g. Holosync have decent entrainment technology, but make ridiculous claims and are very salesy and pushy...  I have tried several and always come back to the Monroe Institute and their well tried and tested sessions, mainly from the gateway experience and lucid dreaming series.
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.
Attention and learning ability has been suggested to improve as a result of beta stimulation protocols. Research has shown that beta waves tend to be deficient among those who have learning disabilities and/or attention deficits. Other research with photic stimulation determined that stimulating 14 Hz and alternating it with 22 Hz over several sessions produced significant GPA improvements.
Targeted hemispheric changes: Some speculate that specific alterations in brain waves can be made on an individual basis. In other words, you can target one frequency in one hemisphere (via the right ear) and another distinct frequency in the other hemisphere (via the left ear). The left ear affects the right hemisphere and right ear affects the left hemisphere.

Hi Julie! You’re very welcome for the info. In answer to your question, I think some are probably good, and some not so good. There are many people putting brainwave entrainment out there these days and it is not so easy to figure out which ones are and aren’t of reliable quality without investing time and doing some research. I would say (in general) that paid products are probably better quality than free ones, but I couldn’t guarantee this is a golden rule. My best advice is to just do your research before spending too much time listening to the freebies.
Our brains follow cues from outside stimuli, and brainwaves mimic the pulse rates of the sounds we expose it to. So, by creating tracks that pulse sound waves at a desired frequency, we can effectively coax our brain into that state. In layman's terms; by listening to some strange sounding brainwave frequency audios, we can literally slip our brain into a state of feeling calm, alert, focused, energized... and the list goes on. Pretty cool, right!?
4. Be hesitant committing to any BWE system making wild claims. Profit fueled marketers with little to no experience in the BWE field have created a slew of low-quality entrainment systems on the market. These products typically make outrageous promises such as permanently enhancing the brain within minutes of use. Although BWE is a powerful method to improve the mind, it’s not a magic bullet.
In addition, Western culture reinforces thought and communication styles associated with the left brain hemisphere, which controls logic, language, and linear thinking in a majority of people, as opposed to the right hemisphere which controls brain centers for emotional, intuitive, creative, and non-linear thought processes. Note that a significant minority of people has the opposite hemispheric dominance than the majority of people.
The specific benefits and claims from this technology are often disputed and considered scientifically questionable. One problem is that there are few experiments that have utilized brainwave entrainment for the purpose of treating a specific psychological ailment (e.g. insomnia). And the experiments that have been conducted are largely backed by corporations that sell the software; hence it could be speculated that there are conflicts of interest.
my daughter had an EEG and the neurologist said the brain wave activity in the back of her brain was very slow. I want to find out what causes this. She had a brain injury (3 skull fractures that were in the right side of her head and across the front right side. The fractures were closed wound. She had a small amount of swelling which diminished on it’s own. The neurologist asked if the fractures were in the back of her head and I told her no. She had no explanation for me.

Controlled or pre/post studies of the effects of BWE using auditory or visual stimulation were eligible for inclusion, provided pulses of light or tone were delivered at frequencies hypothesised to have a beneficial effect or in line with a protocol addressing clinical outcomes. Studies were required to report clinical or psychological outcomes (measured using standard methods or as deemed appropriate by peer review) and to report statistical analysis. Studies of outcomes such as electroencephalogram (EEG) response or neurotransmitter levels were not eligible. Case studies were excluded.
×