When delta waves are present, our awareness of the external world decreases and shuts off. People with ADD have problems with delta waves occurring when they are trying to focus, and focus and attention become increasingly impossible with stronger delta waves. Studies show a reduction of anxiety, improvements in insomnia, and elimination of headaches when people engage in sessions of delta brainwave entrainment.
Most of our Royalty Free brainwave entrainment music uses an audio technology known as "binaural beats". These binaural beats are embedded in the music in order to bring about desirable changes in brainwave activity, thereby encouraging various states of relaxation, deep meditation or sleep. When played with headphones, you may be able to hear the binaural beats as a subtle pulsing sound beneath the music.
So, what we’re doing is combining these two parts, the awakening of complete stillness and deep relaxation with the rhythmic sounds, and embedding all frequencies within the music from right at the upper limits of human hearing to the lower limits. There is multi-level entrainment within Journey—I’ve layered in everything I know about audio brainwave entrainment into this track. 
... These factors may be the specific frequency of BB; the targeted population-because it is known that older people have different quality of brainwave activity than, e.g., youngsters (Bazanova & Aftanas, 2008;Clark et al., 2004), and the tests used to detect the possible changes in working memory capacity. Based on the research showing a positive impact of alpha-range BB on cognitive functioning, specifically attention, auditory sequential memory, working memory, working memory storage, reasoning ability, cognitive processing and hemispheric synchronization, (Carter & Russell, 1993;Cruceanu & Rotarescu, 2013;Foster, 1990;Kennerly, 1994;McMurray, 2006) as well as on the wealth of research documenting the important role of alpha brain wave activity on vigilance, in-hibitory processes, attention, filtering out irrelevant information working memory, the visuo-spatial component of working memory, perceptual abilities and information processing speed (Braboszcz & Delorme, 2011;Clark et al., 2004;Engle et al., 1999a;Freunberger et al., 2011;Klimesch et al., 2007;Lachat et al., 2012;Oprisan, 2004;Palva & Palva, 2007;Rihs et al., 2007;Sauseng et al., 2009;Tuladhar et al., 2007;VanRullen & Koch, 2003), we believe that BB of a frequency that corresponds to the alpha range of brain activity has a temporary effect on working memory capacity. In our study, subjects were exposed to 9.55 Hz BB stimulation while we measured their working memory capacity through the Automated Operation Span Task (AOSPAN). ...
Delta brain state is related to the unconscious or super-conscious mind. Delta waves are the slowest of all five brainwave frequencies. These brain waves are generated in deep sleep and in very deep meditation. In the sleep cycle, the deepest of sleep states is called “Slow Wave Sleep” (SWS). In this phase, the brain begins producing very slow, large Delta waves. The deeper the sleep, the higher the amount of delta waves. This stage plays a vital role in health and well-being, especially because healing and regeneration processes are stimulated in this state. In the Delta state, you do not dream, you are completely unconscious.
Alpha is the resting state for the brain; it is “The Power Of Now”, being here in the present. The Alpha state is the relaxed state of consciousness essential to stress reduction. It is intensely pleasurable: you are awake but relaxed and not processing much information, with a sort of floating feeling. According to Alpha researcher Dr. Joe Kamiya, the Alpha state is “something like letting go of anxieties”.
Over-arousal in certain brain areas is linked with anxiety disorders, sleep problems, nightmares, hyper-vigilance, impulsive behaviour, anger/aggression, agitated depression, chronic nerve pain and spasticity. Under-arousal in certain brain areas leads to some types of depression, attention deficit, chronic pain and insomnia. A combination of under-arousal and over-arousal is seen in cases of anxiety, depression and ADHD. more...
Practitioners are discovering a number of different areas in which entrainment therapy may bring positive benefits. From managing mental health more effectively through to providing increased mental focus and concentration, it is thought the technique can be adapted according to the specific issues being treated. An improved immune system, enhanced levels of pain management, and a reduction in autoimmune disorders are also thought to be achieved through the therapy, leading many individuals with chronic ill health to consider brainwave entrainment as a non-invasive yet effective therapy.
From a strictly physical/emotional viewpoint, the benefits of meditation include (but are not limited to) such things as greater resistance to stress; less physical illness and improved resilience when illness does occur; better quality of sleep and increased recovery during sleep; a generally magnified sense of well-being; a sharper, clearer mind; increased capacity for learning; improved functioning in daily life; more harmonious relationships; greater control over emotional states, and more.

, that is, the average of the two frequencies. It can be noted that every second burst in the modulation pattern is inverted. Each peak is replaced by a trough and vice versa. However, because the human ear is not sensitive to the phase of a sound, only its amplitude or intensity, only the magnitude of the envelope is heard. Therefore, subjectively, the frequency of the envelope seems to have twice the frequency of the modulating cosine, which means the audible beat frequency is:[5]

Binaural beats, or binaural tones, are auditory processing artifacts (apparent sounds) resulting from the stimulation of the ears with two different sound frequencies. In fact, when two different vibrations are delivered to the brain separately through each ear, using stereo headphones, the two hemispheres of the brain function together to “hear” and perceive not the external sound signals, but a third phantom signal. This resulting signal, discovered in 1839 by Heinrich Wilhelm Dove, is called “binaural beat”. The effect on the brain waves depends on the difference of each tone. For example, if a sound frequency of 300 Hz is played in the left ear and 307 Hz in the right one, then the binaural beat would have a frequency of 7 Hz (“frequency following response”) which corresponds to the Alpha brain state, generally associated with relaxation, visualization and creativity. The beating tone is perceived as if the two tones mixed naturally, out of the brain. For the binaural beat effect to occur, the difference between the two frequencies must be small (less than or equal to 30 Hz), otherwise, the two tones will be heard separately, and no beat will be perceived.
For our ancestors, stress was a survival skill during brief, life threatening situations. Once the danger passed, their stress levels lowered. However, in today’s world, we are constantly bombarded by stressors, such as work deadlines, traffic, and family obligations. We rarely get a break long enough to relax and relieve the stress. The over-activation of our stress hormones have been linked to high blood pressure, heart attacks, lower immunity, depression, anxiety, and more.
It is common for people to try entrainment thinking it is going to produce meditation just because they listened to a track. Often they come away disappointed, feeling that nothing special happened. They decide entrainment isn’t what they were led to believe it was. Or they decide meditation is vastly overrated and for them at least, ineffectual. Their disappointment has more to do with not understanding the principles listed thus far than it does with the effectiveness of meditation and brainwave entrainment.
Practitioners are discovering a number of different areas in which entrainment therapy may bring positive benefits. From managing mental health more effectively through to providing increased mental focus and concentration, it is thought the technique can be adapted according to the specific issues being treated. An improved immune system, enhanced levels of pain management, and a reduction in autoimmune disorders are also thought to be achieved through the therapy, leading many individuals with chronic ill health to consider brainwave entrainment as a non-invasive yet effective therapy.

There's no doubt that brainwave entrainment audio is a great technology for anyone who is interested in encouraging altered states of consciousness and it certainly can help people to reach deeper states of relaxation than they might normally have access to. I myself will often listen to brainwave entrainment music in order to enhance my practice of meditation. But let’s keep a balanced perspective, put all the marketing hype to one side for a moment and acknowledge that there is no brainwave entrainment technology in this world that can make you meditate like a Zen monk “at the touch of a button”, despite what some might like you to believe. The mind is NOT a machine. It moves through various states of consciousness in an organic way and at a natural pace. We certainly can guide and accelerate that process with the use of brainwave entrainment audio, but we cannot control it with the same sort of specificity and immediacy as you might control the speed of the car you drive.

Theta brainwaves in the frequency range of 6 to 9 hertz are known as thalpha waves because of their proximity to alpha waves. They are seen during states of high suggestibility, during hypnosis, and during paranormal experience and are also connected to an increase in human growth hormone (HGH) levels and higher blood flow to the brain. Theta brainwaves sit between the realms of the subconscious and conscious mind, making them an especially useful brainwave state for developing creative thinking, working through emotional problems, and integrating subconscious and conscious experience. 
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.
No. The frequencies are consistent throughout the duration of each music production we offer. It could be argued that a better approach is to change the frequency over time, starting at a higher frequency when the listener is alert and slowly ramping down as the music progresses and the listener becomes more relaxed. So why have we not taken this approach?
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.

Your brain actually has a predominant frequency at which it operates in any given moment; this can be associated with your state of mind. In other words, the emotional state of your mind in any moment, such as feeling happy, sad, frightened, sleepy or excited, can be measured as a frequency and with the right sound technology, you can stimulate the state that you want on command!
Today, EEG machines are used for diagnosing epilepsy and sleep disorders, for determining dosages for anesthesia, and measuring the brain activity of people in comas or suffering from brain trauma. EEG machines also continue to play a role in researching and understanding brainwave entrainment and developing new and better methods for delivering the benefits of this form of brainwave modification. 
Hi Ulka, thanks for your compliment on my article. Unfortunately, I haven’t come across any studies or much discussion about the problem with habituation and isochronic tones and how to overcome it. The consensus among experienced users is to regularly change the frequencies and music soundtracks you listen to. Adding music to the tones does change the waveform you are stimulated with, so that’s one of the main reasons why I provide different soundtracks for my isochronic tones sessions. I have released some tracks which use amplitude modulations in the music, instead of isochronic tones. It might be worth giving them a try if you haven’t already. I have them in a playlist on YouTube https://www.youtube.com/watch?v=Lj5tHl2cuWw&list=PLveg0IEcZWN6OIRZyLkv0BJADY7Q6xFCl.
There are general recommendations for stress management that can be applied in most situations. However, keep in mind that there are individual differences and preferences, so a “cookie cutter” approach should be avoided when making recommendations. A comprehensive stress management program will include specific techniques prescribed on an individual basis, but general stress management recommendations are presented in Table 2.
A more extensive study of over 100 participants who were undergoing general anesthesia for a day procedure, reported a decrease in pre-operative anxiety. The participants in this study listened to 30 minutes of binaural beats before surgery, but the researchers noted that people experiencing high levels of pre-operative anxiety could listen to binaural beats for up to 1 hour before anesthesia to reduce levels of anxiety.
Passively listening to binaural beats may not spontaneously propel you into an altered state of consciousness. One's subjective experience in response to binaural-beat stimulation may also be influenced by a number of mediating factors. For example, the willingness and ability of the listener to relax and focus attention may contribute to binaural-beat effectiveness in inducing state changes. "Ultradian rhythms in the nervous system are characterized by periodic changes in arousal and states of consciousness (Rossi, 1986).

By simultaneously combining the sounds of two didgeridoos, a desired state of consciousness can be induced in the listener. For example, when one didgeridoo is played in the key of Bb (fundamental frequency of 58 Hz) and a second didgeridoo is played in the key of C (65 Hz), the difference between the frequencies is manifested as a subtle pulsing (in this case 7 Hz). The listener’s dominant brainwave state will sync with this pulsation in a frequency-following response known as brainwave entrainment.
People who handle stress well tend to employ what stress experts call an "optimistic explanatory style." They don't beat themselves up when things don't work out in their favor. So instead of using statements that catastrophize an incident, like "I'm a complete failure," they might say to themselves, "I need to work on my backhand." Or they'll transfer blame to an external source. Rather than saying, "I really blew that presentation," it's, "That was a tough group to engage." Replace the word "expect" with "hope." Expectations can only be used for those things over which you have the greatest personal control. You can expect to quench your thirst with a drink of water. You cannot expect to get the job you just interviewed for. You can hope to get it.
When people begin to believe these kinds of claims it is only half a step further for them to begin to attribute all of their own curious little experiences to entrainment. After all, they reason in the back of their minds, if 3.84Hz can cure an ovarian cyst, isn’t it just as reasonable that listening to a track at 8Hz might cause the room to appear to spin and change colors? There is an old saying that suggests that the more outrageous a claim is, the more people will be inclined to believe it. Don’t fall for outrageous, ridiculous claims. If you do you’re heading for disappointment, guaranteed.
Start by kneading the muscles at the back of your neck and shoulders. Make a loose fist and drum swiftly up and down the sides and back of your neck. Next, use your thumbs to work tiny circles around the base of your skull. Slowly massage the rest of your scalp with your fingertips. Then tap your fingers against your scalp, moving from the front to the back and then over the sides.
With its focus on full, cleansing breaths, deep breathing is a simple yet powerful relaxation technique. It’s easy to learn, can be practiced almost anywhere, and provides a quick way to get your stress levels in check. Deep breathing is the cornerstone of many other relaxation practices, too, and can be combined with other relaxing elements such as aromatherapy and music. While apps and audio downloads can guide you through the process, all you really need is a few minutes and a place to stretch out.
So, in summary, binaural beats certainly do not work the way the sellers claim, but there's no reason to think they're any less effective than any other music track you might listen to that effects you in a way you like. If they make you sleepy (like they all do for me), use them to go to sleep. If they relax you or get you amped, use them for that. But don't expect them to be any more effective than regular music. If someone you know claims that they are, put them to the test, and bust the myth.
People who are new to meditation sometimes complain that they find it too difficult to silence their thoughts. This is perfectly normal and in fact, if you are new to meditation you should not expect to achieve absolute mental silence in the next day or two. Even the most experience meditators still have their good days and bad days when it comes to meditation and a certain amount of mental activity during meditation is quite normal.

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]