Brainwave entrainment through audio can be triggered through a variety of techniques, including binaural beats, isochronic tones, monaural beats, and modified audio tracks. The brainwavetones are embedded into the audio and the listener is unaware of their presence. He or she simply enjoys the audio track as a pleasurable listening experience, while the various tones generate frequencies in a way that encourages the brainwaves to respond and “get in step.”
Further experimentation showed that the difference between the two frequencies must be relatively small – under 30 hertz – for it to be perceived as a “beat”; frequencies with greater difference are perceived separately. Using binaural beats in various mental states while being recorded by an EEG (encepl…blahFIX) allowed researchers to further delineate the different wavelengths the human mind generates for different states of being. The categories are generally agreed upon as (from most to least “active” states): Gamma (extreme emotions or intense concentration), Beta (active thinking, concentration, anxiety, arousal), Alpha (drowsy, falling-asleep feeling, sometimes also general relaxation), Theta (dreaming sleep or deep meditation), and Delta (deep, dreamless sleep), but the wavelengths at which each occurs are not set in stone, though they generally run as over 40 hertz for Gamma, 13 to 29 for Beta, 7 to 13 for Alpha, 4 to 7 for Theta, and under 4 hertz for Delta.

Thanks for your appreciation of what I’m doing. I’ve been asked for help with autism a number of times over the years, so it’s something that I’ve often looked into and tried to find new information about. Unfortunately, I’ve yet to find any specific research relating to it and using the type of brainwave entrainment tones I use. There are a number of opinions and claims out here, but I’ve often found them to be conflicting. While some are recommending higher frequency gamma waves, others are recommending lower frequency alpha and theta waves while meditating.
In the last two posts, I discussed some unusual ways in which some people respond to certain very ordinary sounds. In the case of ASMR, sounds like tapping, tearing, and popping can lead to tingling sensations associated with relaxation and even drowsiness. In the case of misophonia similar sounds, like swallowing and lip-smacking, can also cause a tingling sensation, but one accompanied by disgust and even rage. Binaural beats are a different kind of sound and many people report finding certain of them relaxing and even conducive to falling asleep.  Other people do not like them and after hearing them once never want to hear them again. 

If you name your emotions, you can tame them, according to new research that suggests why meditation works. Brain scans show that putting negative emotions into words calms the brain's emotion center. That could explain meditationÕs purported emotional benefits, because people who meditate often label their negative emotions in an effort to let them go.
The following is an example of binaural beats incorporated into an actual piece of music and had even made the headlines as “the most relaxing song ever”. The song is called “Weightless” and is composed by the band Marconi Union, reportedly in collaboration with sound therapists. The official explanation is that the track would start on 60 beats per minute and slowly but surely slow it down to 50.
Over the long term, traditional eastern methods (such as meditation and yoga) train your brainwaves into balance. Of the newer methods, brainwave entrainment is an easy, low-cost method to temporarily alter your brainwave state. If you are trying to solve a particular difficulty or fine-tune your brainwave function, state-of-the-art brain training methods like neurofeedback and pEMF deliver targeted, quick, and lasting results.  

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“.
The brain is composed of millions of specialized cells called neurons. Neurons send signals to other neurons using electro-chemical messengers called neuro-transmitters that attach to receiving sites located on the neurons themselves. There is a space between the end of the neuron and the receptor called the synaptic gap. As neuro-transmitter chemicals move across this gap, a small electrical charge is created. 

You may have experienced Theta right before drifting off to sleep, during a lucid dream, or during a deep meditation. In Theta, you no longer sense the outside world, but you are aware and conscious of your internal world. All of your subconscious fears, hopes and judgments are hidden in the Theta state. Theta is a difficult state to achieve because you often drift out of it very quickly either becoming conscious in Alpha or moving on to the next deeper state. By staying in Theta, you can learn endless information about yourself and your consciousness.

4. Theta State: (4 — 8Hz) We're able to begin meditation. This is the point where the verbal/thinking mind transitions to the meditative/visual mind. We begin to move from the planning mind to a deeper state of awareness (often felt as drowsy), with stronger intuition, more capacity for wholeness and complicated problem solving. The Theta state is associated with visualization.
Alpha Waves are electromagnetic oscillations in the frequency range of 8Ð12 Hz arising from synchronous and coherent (in phase / constructive) electrical activity of thalamic pacemaker cells in humans. They are also called Berger's wave in memory of the founder of EEG. They place the brain in states of relaxation times, non-arousal, meditation, hypnosis
At the beginning of May, I decided to change over to EquiSync because it’s much cheaper and let me experience the deeper levels sooner. At best, my blood pressure has been down to 66 and after cups of tea and food, back up to 76-80 which is regarded as acceptable. I was able to achieve these wonderful results in less than 6 months of daily practice of meditation using audio-beat technology.
A newer alternative to binaural beats is isochromatic tones. These are tones that are interspersed with periods of brief silence, creating a similar effect to binaural beats but without the two frequencies playing in different ears. Because isochromatic tones do not need headphones, they are gaining popularity as the newest method of brainwave entertainment.
All brainwave frequencies are useful and beneficial at certain times – there is no brainwave that is intrinsically better than another. However, by deliberately choosing to attain a particular brainwave state, a corresponding mental state can be brought about at the same time. For example, a working person who has been in an overly alert beta brainwave pattern for many hours can quickly shift their mind and body into a relaxed state by listening to a few minutes of brainwave entrainment music for inducing alpha or theta brainwaves.

... The goal of the study was to observe the effect of exposure to BB on working memory capacity. As suggested by many studies, BBs corresponding to alpha brain waves can positively influence cognitive processing, namely attention, auditory sequential memory, working memory, working memory storage, and reasoning ability (Carter & Russell, 1993;Cruceanu & Rotarescu, 2013;Foster, 1990;Kennerly, 1994;McMurray, 2006). The results show that a BB of the frequency of 9.55 Hz – which is a representation of the alpha frequency range of the brain activity – had a temporary positive effect on working memory capacity in our sample of healthy, adult university students. ...
One of the first pieces of research into using binaural beats as a sleeping aid was In a paper called “Tests of the Sleep Induction Technique” published in 1975 by Dr Arthur Hastings. He noted the effects of subjects who listened to a tape containing binaural beats starting from beta slowly descending to delta. Using an EEG machine he was able to monitor the subject’s brainwaves as they listened to the tape, becoming increasingly relaxed before falling asleep. He concluded; “patterns in the various stages suggested that the tape was influencing the subject’s state”.
^ Jump up to: a b Fox, Kieran C.R.; Nijeboer, Savannah; Dixon, Matthew L.; Floman, James L.; Ellamil, Melissa; Rumak, Samuel P.; Sedlmeier, Peter; Christoff, Kalina (2014). "Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuroimaging in meditation practitioners". Neuroscience & Biobehavioral Reviews. 43: 48–73. doi:10.1016/j.neubiorev.2014.03.016. PMID 24705269.
While a practical understanding of brainwaves has been around for as long as people have been singing, chanting, and drumming, a scientific view of the electrical activity inside the human brain was not published until 1924 when German psychiatrist Hans Berger developed a machine for sensing and recording activity in the brain by attaching small electrical sensors to the scalp of his patients and recording the resulting electrical activity. Berger’s inventions and discoveries were built upon the earlier work of Richard Caton who published animal studies on brainwave oscillations in 1875.
A common element in recordings incorporating alpha and theta frequencies is a steady but barely perceptible rhythm of the frequencies themselves. This subtle and calming pulse mixes with sounds of gentle breezes, distant bird songs, and the slow progression of deep synth notes. Underneath this, below the audible sounds at sub 16 hertz levels, other frequencies intermingle, deepening the merging of conscious and unconscious mind.
The binaural beats sleep package is a pack of four binaural beats audio sessions. It’s produced by the Unexplainable store, a popular binaural beats online store. They’ve been in business since 2007, selling a vast range of binaural beats for sleep relaxation and meditation. They have some real gems if you can look past the excessive new age marketing.
Thanks for the coupons, I had originally looked into these cd’s after my doctor recommended them, but my mom wound up buying them for me for Christmas (she didn’t know about the coupons I had!) Anyway just listened to Equisync II today for the first time, I was in such a state as to where I didn’t know if I’d fallen asleep or not! I hadn’t but was in such an amazing place.
You’ve heard me talk before about how sound can make a difference to sleep. Patients often tell me that they fall asleep to relaxing music, they seem to find it really helps them let go of active thoughts and quiet their mind—which, like yours probably does, tends to race from one thing to the next all day long (aka I can’t turn off my brain syndrome).
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.