We can’t always control sources of stress in our lives, but we change how we react to them. The good news is this: The human body is actually designed to experience and handle stress, which is exactly why our bodies react to it so strongly. With some practice, we have the power to learn to use certain elements of stress to our advantage (for example, the fact that stress keeps us more alert and attentive), while better controlling other negative reactions (like digestion problems or giving in to cravings for unhealthy foods).
When you hit a tuning fork, tuned to a particular sound frequency such as the note B, and hold it close to the strings of a guitar, you will notice that the B string on the guitar will vibrate because it has entrained on to the same frequency of the tuning fork. Interesting enough, the other strings will not vibrate. Only the one with the same tuning as the tuning fork.

There is a lot to like about this technology as a potential treatment for sleep problems. It’s low impact and non-invasive, it doesn’t rely on chemical drugs, it’s inexpensive and for most people likely easy to adopt and maintain. In this way, it’s similar to the other behavioral therapies for sleep that I like so much, including meditation and relaxation techniques, and other mind-body therapies.
While the physiological and psychological processes being uncovered by brain science in the study of brainwaves is sometimes complex and still being investigated, certain basic principles are well-established, easily understood, and helpful for achieving the most effectively use of brainwave entrainment when seeking relaxation, improved sleep, lowering of anxiety, or other goals. This important background information and scientific knowledge presented here includes: 
Gamma waves are the fastest brainwave frequency range. Gamma brain waves are believed to link and process information from all other parts of the brain. A high amount of gamma wave activity in the brain is associated with intelligence, compassion, focus and feelings of happiness. High levels of gamma brain waves have also been linked to improved memory and an increased sensitivity to sensory input. Low amounts of gamma brainwave activity have been linked to learning difficulties, poor memory and impaired mental processing.
In addition to potentially boosting sleep-promoting hormones, binaural beats may also reduce our perceptions of pain. A 2017 study found binaural beats used in combination with visual stimulation led to reductions in patients’ perception of acute pain. Other recent research showed binaural beats helped improve pain perception in patients with chronic pain.
That is generally where the science ends and the pseudoscience begins. A number of companies and individuals have then extrapolated from the phenomenon of entrainment to claim that altering the brain waves changes the actual functioning of the brain. There is no theoretical or empirical basis for this, however. Entrainment is a temporary effect on the synchronization of neuronal firing – it does not improve or increase brain functioning, it does not change the hardwiring, nor does it cure any neurological disorder. There is no compelling evidence for any effect beyond the period of entrainment itself.
I appreciate your compliment on my article Henry. I’ve been using and reading up on isochronic tones and brainwave entrainment for many years, so it was just a case of trying to put a lot of what I’ve learnt into one article. I don’t have a great deal of knowledge or experience in using hypnosis and subliminals, so I’m afraid I wouldn’t be in a position to create something so extensive in reviewing them.
In physics, entrainment is the process of two oscillating systems coming to assume the same periodic rhythm, such as is observed when two clocks slowly synchronize their ticking and tick together in harmony after some time. Pendulums also achieve this same synchronicity when swinging in close proximity to one another, a phenomenon first observed and written about in 1665 by Christiaan Huygens, a Dutch scientist.
There are many advantages and disadvantages with binaural beats. One of the major advantages is hemispheric synchronization. Since both hemispheres are required to create the beat within the brain, this method is an excellent way to create greater harmony between areas of the mind typically functioning independently. Binaural beats are also known to have effective hypnotic and relaxing effects.
If you’re going to enter a state of meditation, a technique of some sort must be employed that takes you there. (Note – I am fully aware of references to “spontaneous enlightenment experiences”, but these are an entirely different category of phenomena than what is being discussed here and are outside the scope of this discussion. Perhaps another time.)

What the Neuro Programmer does (as far as I can tell – access to much of the website requires the purchase of product) is present sound and visuals on the computer screen. The user is meant to passively view and listen to this while their brain is effortlessly programmed to solve whatever problem they are having or improve whatever performance they are interested in.
Doing almost any routine, repetitive activity (like vacuuming, shredding paper or knitting), or reciting a word that represents how you wish you felt (such as calm) is a quick way to achieve a Zen-like state. Studies show the effects lower blood pressure and slow heart rate and breathing. The crucial elements are to focus on a word, your breathing or a movement and to bring your attention back to your task if your mind wanders or negative thoughts intrude. Or look to your faith for a mantra: A recent study published in the Journal of Advanced Nursing found that repeating phrases with spiritual meanings helped participants cope with a range of problems, from anxiety to insomnia.
The composer Alvin Lucier has written many pieces that feature interference beats as their main focus. Italian composer Giacinto Scelsi, whose style is grounded on microtonal oscillations of unisons, extensively explored the textural effects of interference beats, particularly in his late works such as the violin solos Xnoybis (1964) and L'âme ailée / L'âme ouverte (1973), which feature them prominently (note that Scelsi treated and notated each string of the instrument as a separate part, so that his violin solos are effectively quartets of one-strings, where different strings of the violin may be simultaneously playing the same note with microtonal shifts, so that the interference patterns are generated). Composer Phill Niblock's music is entirely based on beating caused by microtonal differences.
No, it isn’t, at least not in the way these people are thinking. Neither would any other entrainment product you could purchase for that matter. Part of the problem is the proliferation of utter nonsense about brainwave entrainment one can read all over the internet. There is one site in particular that comes to mind, and the contents of that site are often copied by other websites. It is a list of Hz frequencies with their corresponding (alleged) physical effects. The list runs on for many pages. I won’t bother with the link because you can Google it and find it for yourself if you feel the need for a good laugh, but here are some examples regarding meditation and brainwave entrainment from this site:
Brainwave entrainment is a colloquialism for such 'neural entrainment', which is a term used to denote the way in which the aggregate frequency of oscillations produced by the synchronous electrical activity in ensembles of cortical neurons can adjust to synchronize with the periodic vibration of an external stimuli, such as a sustained acoustic frequency perceived as pitch, a regularly repeating pattern of intermittent sounds, perceived as rhythm, or of a regularly rhythmically intermittent flashing light.