In simplest form, they are an audio technology which are used for (safe) brainwave entrainment. Our subconscious mind operates, throughout the day and night, in various brainwave state frequencies, measured in cycles per second (Hz) These frequencies range from the slowest (Delta) frequencies experienced in deep, dreamless sleep and in deep meditation where your conscious-awareness is fully detached, to the fastest (Gamma) frequencies associated to stimulating flow states, high-level thinking and information processing. There are actually 5 known brainwave state frequencies each having their own set of unique characteristics:
That all said, we are all different and have our own different limits. So I generally advise that you just be aware of how you are feeling, and if you feel like you are getting a bit fatigued from it, it’s probably time to stop or at least take a break. When listening over long extended periods, I recommend that you keep yourself well-hydrated. Your brain needs a good supply of water to function well, especially if you are studying hard and increasing your brainwave electrical activity.

I tried other companies the last few years or so….among the likes that mainly used binaural audio and the deepest I was really ever to achieve was alpha state….maybe theta once or twice over the last few years. It takes incredible dedication and practice to achieve the deep, renewing states of meditation that are most sought after…..I listened to the theta meditation mp3 last night and within what seemed like a few minutes my mind was flooded with imagery…memories long gone…my body was sleeping, heavy as lead, but my mind was crystal clear, aware of my surroundings. I could barely even open my eyes!
I also believe that the dangers of brainwave entrainment should be further explored as well. There are relatively vague benefits, but it remains unclear as to whether entraining certain frequencies may be detrimental to performance or induce harm. Despite the fact that brainwave entrainment has existed for a long term, it remains an understudied niche in neuroscience.
Different people have different requirements when it comes to frequency changes in the music and it's quite impossible for us to anticipate them all. We would need to produce so many different variants of all our music productions that it would be impractical to manage and confusing for our customers. For example, if we were to start raising the frequency from theta up to alpha between the 50-60 minute mark of a piece of music, this would be useless to someone who used the music for a guided meditation that was only 45 minutes long. In the early stages of the development of our brainwave entrainment music we had so many different requests from different people that we could only opt for the simplest solution, which is to use a consistent frequency throughout. It might not be the absolute "perfect ideal", but this is still a very effective technique and the feedback we've received on our brainwave entrainment music has always been exceptionally positive.
1. Compressed formats like MP3 do not retain the sound quality necessary for the brain to fully achieve brainwave synchronization – and are too inferior to effectively deliver even binaural beats downloads or isochronic tones properly, much less something as powerful as NeuralSync™. Our lossless audio entrains at the precise level guaranteed to induce the most potent response.
Relaxation: There is already evidence that brainwave entrainment helps improve relaxation. In studies analyzing short-term stress and anxiety, significant improvements were noted. This has been verified by other studies that suggest brainwave entrainment enhances muscle relaxation in biofeedback and can help with pain reduction and migraine headaches. The relaxation-induced response of entrainment may be responsible for a variety of the benefits.
Transparent Corp's Research Area is arguably the most comprehensive resource for collated brainwave entrainment research.   Update: the main research area on Transparent Corp's website is currently being updated, so it is offline.  However, you can still access their peer-reviewed research paper as a PDF here: “A Comprehensive Review of the Psychological Effects of Brainwave Entrainment“.
Deep relaxation is a major benefit resulting from the brain’s cortical frequency following response. By selecting the desired rate the brain, via the frequency following response, will tend to mimic the rate it is exposed to and thus enter that brainwave state. This helps to explain why this technology can produce benefits commonly found with meditation. One of the most valuable benefits of consistent  brainwave entrainment is that we are able to experience and recognize the various states of consciousness. With practice we can learn how to re-create these states.
There appeared to be some evidence that 10 Hz stimulation (alpha waves) improved anxiety, but it wasn’t statistically significant. A study that utilized a ramping format of alpha to theta to delta waves (over the course of 10 minutes) found a significant improvement in anxiety. In terms of long-term stress, there is evidence that alpha and beta stimulation improved measures of “competence” and “emotional exhaustion.”
Isochronic tones are the most recent and advanced method for brainwave entrainment audios. With isochronic tones, the same intensity is used for all tones, but they pulsate on and off at different rates. The speed, pattern, and rates of these tones can be changed and altered throughout the recording, and the brain will follow them into desired states. The use of isochronic tones opens up the ability to lead the brain into highly specific states, at specific speeds and intensities. This has opened up the doorway to producing both dominant and subdominant waves(i.e. an alpha brainwave state with subdominant theta waves), and the ability to lead the brain through different waves, at specific speeds (i.e. holding the brain in an alpha state for 10 minutes, then dropping it through theta for 20, and holding it in delta for five before bringing it back into alpha at the end of the recording.) This allows thousands of different possibilities in training the brain, and also makes the process of listening to these types of audios more natural, and more powerful. 
I love your tapes! I bought them a few weeks ago and have greatly benefited. I’m also a holistic practitioner and have recommended them to a number of patients. And today when I made my last referral to your website for them to purchase from, it occurred to me that perhaps you have referral discounts, or wholesale prices for practitioners, and that I should ask?
Hi Et, In all the feedback and studies I’ve read and looked into over the years, I’ve seen lots of feedback from people talking about how they don’t like the sound of the tones, or they find them irritating in some way. Unfortunately, there doesn’t seem to be any particular reason why one person likes it and the next doesn’t. It’s a bit like normal music, one person’s sweet symphony is another person pneumatic drill. It’s common for people to find it weird and maybe annoying at first, which is how I felt in the beginning. But usually after a few listens you can start to get used to it and appreciate the sound, and especially the feeling it gives you. Personally, I think it can help if you try to embrace the sound, psychologically speaking beforehand. It can also help to have the sound playing at a very low volume, to begin with, then building it up as you get more used to it.
Brainwave Entrainment audio technology was first developed and introduced to the public decades ago by Robert Monroe, through the Monroe Institute.  This organization used their brainwave entrainment audios as a tool to induce people into specifically directed out of body experiences as well as train remote viewers. Since then the crafting of brainwave entrainment audios has become a sophisticated art. These audios are now created and used by a number of businesses and individuals for a variety of purposes, most of which having to do with personal development and self-help.
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]
×