The brain produces electrical signals. These signals change depending on what we are doing and what mental state we are in. For instance when we sleep these signals are different from when we are awake. This brain activity can be measured with EEG. It will output in Hz (Hertz - cycles per second) these electrical signals. The most dominant brainwaves will tell us what sort of state a person is in. The slower vibration (lower Hz), the more relaxed that individual is. Using audio technology we get the brain to start following the beats or pulses in a sound if done exactly right.

Since the beginning of this year, I’ve been doing meditation with the help of audio-beat technology from a well-known brand, which I thought was a bit expensive. But, at least it gave me an insight into how the mind could and would give me an edge in solving most of my problems. From February, I decided to double the dosage to that which was recommended by the firm as I was desperate for a cure.
Business executive and radio producer Robert Monroe started experimenting with brainwave entrainment and has a series of powerful out of body experiences using it. In 1971 he published his cult classic “Journeys Out of the Body” sharing his experiences. He later created one of the first audio entrainment companies called Hemi Sync, alongside the Monroe Institute of Applied Sciences.

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.

Isochronic tones work just the same in delta as they do in alpha, theta and beta and they are widely used in the brainwave entrainment community to help people sleep. Like you, I’ve also seen some websites saying they don’t work in delta, but it’s a bit like the game of Chinese Whispers, where someone makes a comment and then after it gets passed around and shared a lot the message gets distorted and appears to be a fact. I don’t know of any scientific reason why they wouldn’t work in delta. I remember some people talking about this on a brainwave entrainment forum many years ago. They were saying they found isochronic tones a bit too abrupt for using to help them sleep and they preferred binaural beats, as they thought they were a more soothing sound. That was just a personal preference shared by a couple of prominent forum members at the time and some people then took that as a fact for everyone. That’s where I think that belief originated from.
Since most of us spend our days in the beta state, EquiSync excludes the beta brainwave frequencies, and entrains only those responsible for the most beneficial brainwave states: alpha, theta, and delta waves. The two charts on this page illustrate the basic benefits of each brainwave state as well as the basic targeting of the EquiSync programs 1, 2, & 3.
When the body-mind effects from experiencing AVE are fully appreciated, the experience becomes as regular and beneficial as many other life essentials such as quality sleep, good nutrition, pure water and exercise. Sleep is another area where AVE has been shown to be beneficial, contributing to the natural regenerative process of the body and brain.
I loved it All However because of serious blood pressure issues one of those beats isn’t doing well with my chest. Im getting pains. I want to BELIEVE that it flowing thru and because like everything in life gotta go thru some pain and discomfort to true set the negative vibes free. Thats what I think however could be wrong not an expert at this yet but can BECOME One overtime with Practice.
The brain has two hemispheres that operate somewhat independently from one another. The two hemispheric structures of the brain are connected by a large nerve, called the corpus callosum, which sends information back and forth between the two sides of the brain. In most people, the left hemisphere controls language, logical thinking, and analytic processes and the right side contains the centers for emotion, intuition, and non-linear creative thinking.
When the body-mind effects from experiencing AVE are fully appreciated, the experience becomes as regular and beneficial as many other life essentials such as quality sleep, good nutrition, pure water and exercise. Sleep is another area where AVE has been shown to be beneficial, contributing to the natural regenerative process of the body and brain.
Isochronic tones and Monaural beats are now being considered by many to be more effective and more useful in brainwave entrainment technology. Monaural beats, unlike binaural beats, only use one beat. It is said that these are easier on the brain, and help to induce a specific brainwave state faster and more effectively, as the brain does not need to go through the process of reconciling two different frequencies. 
 Theta brainwaves are the next level down from alpha, at a range of 4Hz-8Hz. These brainwaves commonly occur just before sleep, or in the lighter stages of sleep. They also occur while you are day dreaming, or when you experience a strong emotion. It is not so common for an adult to produce prolonged theta brainwaves unless they are an experienced meditator, or perhaps deeply involved in an intuitive art such as music or painting. A dominant theta brainwave state is one of deep relaxation (deeper than alpha) and natural healing. In prolonged dominant theta states, the brain’s sodium/potassium ratio resets and balances itself, curing mental fatigue, and improving the brain cells ability to transport and exchange neuro-chemicals. Without the means of deep meditation, or brainwave entrainment technology, this benefit would only otherwise come from sleeping or napping.Theta is known as the one of the best states for communication with the subconscious mind.
I typically feel overwhelmed by the numerous things that need to be accomplished, which leaves me feeling anxious and rushed. This particular combo has really helped me to slow down today and not feel so uptight, which sadly, is not easily accomplished. I use other modalities to shift my body into parasympathetic mode, but I can't seem to stay there. This program seems to be helping dampen down triggers that cause my body to shift into sympathetic state inappropriately.
For me, brainwave entrainment actually helped me more easily meditate on my own without the technology. There is definitely evidence to suggest that the neural pathways that form from listening to these audios aids the brain in better producing these brainwaves on its own moving forward. Though I used brainwave entrainment for several years, almost daily, there was also a point in my life where I went without the technology and meditated daily on my own. I believe that even this practice was accelerated drastically by my listening to bwe in the past.
* Headphones/Earbuds are Required for Binaural Tones to be Effective as the Left Ear and Right Ear Audio must be isolated for the Brain to perceive the inaudible low-frequency difference between the two sides. ** Changes to Orientation Support: With the upcoming arrival of several new devices with new screen-sizes and aspect ratios, iOS 8 required a re-write of our iPhone and iPad UI to support these devices, and as part of that, we have returned the app to a Portrait-only view for now. Once we know what these future screen dimensions and Aspect Ratios are, and have time to work with the real devices, we can implement a new Landscape UI for the iPad.

- Added the ability to create a playlist of your own iTunes library music and use it as background. The behavior of the app with iTunes music is used instead of, or combined with our included ambience, is slightly different so please review the help. Notably, unlike our included ambience which can be played at a volume below the device volume, iTunes audio can only be played at the device volume. So when in iTunes mode the Ambience volume slider disappears.

Although most experts will tell you that people can get through the day without the production of Alpha brainwaves, that doesn’t mean there won’t be any repercussions. For people who have suppressed production of these brainwaves, they can end up developing anxiety disorders and other stress-related diseases, which can lead to the weakening of their immune system.

My personal experience of this was that it could get very harrowing; at times, I would literally be gritting my teeth and contracting my ribs while I was in meditation, because it was pushing me so hard. I began to ask, “Is it necessary to push this hard in such a static way and create overwhelm over such prolonged periods in order to propel spiritual evolution?”
In 1956, the famous neuroscientist W. Gray Walter published the results of studying thousands of test subjects using photic stimulation, showing their change in mental and emotional states. He also learned that photic stimulation not only altered brainwaves, but that these changes were occurring in areas of the brain outside of vision. In Walter’s words:

If you find that you are really heavily into overwhelm, you can just turn the volume down and meditate with the biofield amplitudefrom your iPod, CD player, PC, or Mac transmitting a very healing biofield technology that allows you to dig deeper into meditative states without putting your nervous system on edge. Now you are pushing and purifying your nervous system without bludgeoning it.
If you're struggling to focus and feeling a bit tired and unmotivated while studying, you can help boost your concentration and energy levels by increasing Beta activity.  The SMR range is right at the bottom of the Beta range, so it's not too intense, and so is ideal for playing in the background and using as a general study aid.  If you are looking for something a bit higher for a more intense focus session, try my Study Focus isochronic tones session, which uses frequencies between 14-17Hz.
Hi. This article contains a lot of information about brainwave entertainment. Thanks. I have a question. I downloaded an Android app that plays isochronic tones. I like to use an Isochronic tone at 2.5Hz that is in Delta range and is supposed to help me get a deep and dreamless sleep. I use it without headphones and just keep the smartphone next to my pillow. But I do not know if I should keep the tone playing all the time while I sleep or put it on timer to shut off after some specified time. A custom timer is possible with the app. Can you please guide me.

Thanks for the reply. I am now clearer on ‘what’ is heard. Can you expand or point me in direction ..a bit more about ‘pitch frequency’ and frequency spoken about and what exactly is the difference ..and how we use the higher pitch frequencies to ‘hear’ or become aware of them? Would you only pick up the low freq on a EEG?. sorry for being pedantic still does not clear up split isochronics and possibly creating same situation as binaural beats..
Sir, am a user of subliminals from last 3 months. I’ve used subliminal with and without binaural beats.i found it more effective without binaural beats.and i got results too. But from last few weeks am listening to few subliminals with binaural beats.i donno why ..but i started feeling severe pain on my head and feels too tired and drowsy. I thought its because as it works. But my condition was getting worse. And also I started having fear and scary dreams. I started feeling like too stressed . I listen to 6 subliinals for 6 subjects a day. I read in a website its not a problem to listen 6 subjects a day.and i listen 6 subs for one hour each too…but in the starting i was happy with my results and subliminals.but now am getting scary dreams ..peaceless and fear. Why is this sir. Plse help me…but i love to use subliminals again as i got results. But am scared now. And plse also tell me sir if its okie to use subliminals without binaural beats?? Will they have same effect?? Help me sir…
it says the following: “Running a delta sleep session throughout the night is not recommended as it can interrupt the normal sleep cycle”. I’ve been looping pure delta isochronic tones for about 5 days now, and have had quality sleep. Should I continue looping delta or should I let the videos play out without looping them? Will it will harm my health to do loop delta while I sleep?
Audio-Visual Entrainment (AVE) is a technique that utilizes pulses of light and sound at specific frequencies to gently and safely guide the brain into various brain wave patterns. By altering your brain wave frequencies, you have the ability to boost your mood, improve sleep patterns, sharpen your mind and increase your level of relaxation, all with the simple push of a button!
I am fortunate to be working with Deepak Chopra, M.D., and Dr. Rudy Tanzi, co-authors of the bestselling book Super Brain, on a technology called Brain Wave Entrainment. Deepak is very well known, but Rudy is an amazingly interesting person as well. He is the Kennedy Professor of Neurology at Harvard Medical School and Vice-Chair of Neurology at Mass General Hospital. Rudy co-discovered three of the four original Alzheimer's genes and today runs the Alzheimer's Genome Project. He also plays the keyboards, including, at times, for Aerosmith. He is kind of a real life "Buckaroo Banzai."
One can also learn to control and slow down their brain waves through various neurofeedback technologies such as electroencephalograph (EEG), galvanic skin response (GSR), and heart, pulse and breath rate monitors. These devices measure stress and relaxation parameters and then "play" back the signals to the user so they can use the signals as a beacon to guide and "steer" themselves into a relaxed state. This takes some time, work and discipline but is much quicker than learning meditation.
Hi Sahil, it’s hard for me to speak about other people’s tracks and videos, as I don’t know how they created them either. If you’re interested in a particular track/video and unsure about it, try asking the creator a question or two about the track, what frequencies were used and for how long, what software they used etc. Then make your own judgement based on how they reply to you. Jason
Years of scientific study combined with the personal testimony of thousands of people establish that using brainwave entrainment techniques positively affects the physical, mental, emotional, and spiritual well-being in a majority of users. You can easily take advantage of these powerful methods of personal self-help and self-improvement by downloading a variety of entrainment music right now.

-Other Specialized Entrainment Methods: There are a few other things to consider like whether the audio creator uses binaural beats, monaural beats, or isochronic tones when appropriate for the desired effect of the audio. Or whether they use other entrainment methods as well, like volume modulation, pitch modulation, or panning from right to left of the headphones to further improve the immersion of the audio.
The pitch frequency measures and describes what a beat sounds like, i.e. does the isochronic beat have a deeper bass sound, or is it high pitched and sharper sounding? The beat waveform frequency describes how many times the beat is repeating per second, i.e. how fast it is beating. You don’t really need to concern yourself about the pitch frequency, as that doesn’t have a direct influence on brainwave entrainment and doesn’t play a part on the measurement on an EEG. I only mentioned it because you were referring to humans not being able to hear below 20Hz. I change the pitch frequency just to suit the mood of the track. For tracks that are to be relaxing, for meditation or sleep, I tend to use a lower pitch frequency so it sounds deeper and more relaxing and I never have that lower than 100Hz. For an energizing, high focus track I might use a more higher pitched 200Hz isochronic tone, because that is sharper sounding and less likely to make you feel sleepy. That’s all you really need to know about the pitch frequency.
I’ve been on the brainwave vibe for about 6 months now, & I’m really diggin’ some results! I find that there are certain frequencies, I guess, that feel right and comfortable to my mind; I also find that I can physically feel the area of my brain that “pure” (no frikkn ocean waves) tones are affecting as I listen to them. This occurs the moment I hear the sound. Kinda like energy, a brain tickle. Spooky & awesome!!
Meanwhile, the therapeutic benefits of listening to sound and music is a well-established principle upon which the practice of receptive music therapy is founded. The term 'receptive music therapy' denotes a process by which patients or participants listen to music with specific intent to therapeutically benefit; and is a term used by therapists to distinguish it from 'active music therapy' by which patients or participants engage in producing vocal or instrumental music.[37] Receptive music therapy is an effective adjunctive intervention suitable for treating a range of physical and mental conditions.[38]