“Binaural beats are not very noticeable because the modulation depth (the difference between loud and quiet) is 3 db, a two-to-one ratio. (Isochronic tones and mono beats easily have 50 db difference between loud and quiet, which is a 100,00-to-1 ratio). This means that binaural beats are unlikely to produce an significant entrainment because they don’t activate the thalamus.”

Therefore we are very receptive to new technology products that promise to improve our lives, or solve previously difficult problems, because of some new scientific or technological advance. This has created, in a sense, a marketplace of consumers that expect to be dazzled with technobabble they don’t understand, backed by assurances of legitimacy by the citing of research and association with professionals or professional institutions, and offering significant benefits. We are all, in a sense, waiting for that next product to improve our lives, and many of us like to feel we are on the cutting edge – getting an advantage over others by being savvy early adopters.

Your brainwave activity during sleep is largely distinct from your brain activity when you’re awake. (REM sleep is one exception to this—during REM, your brain is active in ways very much like when you’re awake.) During non-REM sleep, the slower, lower frequency theta and delta waves dominate, compared to the alpha and beta waves that are prominent when you’re alert and active.
For many years this principle of entrainment has been used as a part of neurofeedback to help patients change their brain wave patterns in the hope of ameliorating the symptoms of dysregulated brain processes that are hypothesized to contribute to various disorders such as ADHD, anxiety, and depression. There is some evidence that neurofeedback combined with photic stimulation (e.g. Hammond, 2000) can help depression and that auditory and visual stimulation can help cognitive abilities in children with learning disabilities (e.g. Olmstead, 2005). 
I first became aware of brainwave meditation programs  and brain waves when researching alternative methods for treating the bipolar disorder I had been unsuccessfully living with my entire adult life. I eventually learned a method of releasing difficult emotions on the spot, which I then practiced extensively, and consequently found it easier and even desirable to meditate for fairly lengthy periods of time. Though I took up meditation as a serious daily practice and experienced many undeniable benefits, I nonetheless intermittently experienced life-debilitating bouts of mania and severe depression, often resulting in chaotic mixed states and an inability to maintain daily social functions. During these times, it became nearly impossible to sit in meditation.
Binaural beats are a type of brain entrainment technology. Entrainment, by the way, is a fancy way of saying "matching". The beats influence your brainwaves, which in turn alter the states of your consciousness. They were first discovered in 1839 by Heinrich Wilhelm Dove, but were considered a scientific oddity until 1973, when Gerald Oster published an article called, "Auditory Beats in the Brain". Oster's work offered new insights, as well as some laboratory findings, to Dove's research; hence, a revolution was started in the field of neurophysiology. Binaural beats are of interest to neurophysiologists investigating the sense of hearing.

Regarding split hemisphere isochronic tones. Think of this as two separate isochronic tones tracks playing independently of each other, one playing in one ear and the other one in the opposite ear. Better still, imagine someone playing and recording a drum beat at a rate of 5 taps per second (5Hz – 5 cycles per second). Then a separate recording of a drum beat is made at a rate of 10 taps per second (10 Hz). You then make an audio track where the left ear/channel hears the 5 drum beats recording and the right ear/channel hears the 10 beat recording. With headphones on, each ear can only hear each respective drum beat and not the other. So you are hearing two different beat recordings at the same time, but it’s different in each ear. A split hemisphere isochronic tones track works just the same. You hear two beats at the same time, not two tones as with binaural beats that create a single beat, but two different speeds of beats in each ear. This is what enables you to stimulate and influence each side of the brain with a different frequency of beat. Binaural beats can only stimulate and influence a whole brain effect using a single beat.
A few months ago I decided to test the ability of the “Equisync II” brainwaves therapy combined with other more traditional self-improvement programs and the results have been even more amazing to me. Currently in my mind I honestly believe this type of therapy can be a breakthrough, or simply the genesis of a new type of therapeutic techniques to correct several psychological, and behavioral human issues including depression, lack of organization, and self-esteem among many, many other possibilities.
Cortisol is an arousal hormone, stimulating alertness and attention. Cortisol levels rise and fall in connection to circadian rhythms—cortisol levels rise to their peak levels first thing in the morning, just in time for you to be active for the day. Too-high cortisol levels are associated with insomnia, as well as more time spent in light sleep, rather than deep sleep.
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.
Let’s say you’re listening to a sound in your left ear that’s at a frequency of 132 Hertz (Hz). And in your right ear, you’re listening to a sound that’s at a frequency of 121 Hz. Your brain, however, gradually falls into synchrony with the difference — or 11 Hz. Instead of hearing two different tones, you instead hear a tone at 11 Hz (in addition to the two tones given to each ear).

In Theta, you are in a waking dream, receptivity is heightened and you are able to access knowledge and information that normally lies beyond your conscious awareness. As flashes of vivid imagery dance before your mind's eye, you may feel a "floating" sensation as your mind expands beyond the boundaries of your body. In this deeply relaxed state don't be surprised to receive sudden insights, inspiration or a sense of knowing.
Theta: This brainwave pattern is associated with deep relaxation and with some stages of sleep, including the lighter stages of non-REM (NREM) sleep. REM sleep itself is mostly composed of beta wave and other activity that’s similar to an alert, waking brain. Deep meditation produces theta waves, which are slower and lower frequency (between 5-8 hertz) than Alpha waves. That murky barrier between sleep and wakefulness, when you’re drifting in and out of sleep, and your thoughts feel dreamlike and difficult to remember? That’s a theta-dominant state of consciousness.
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”.
People who meditate grow bigger brains than those who don't. Researchers at Harvard, Yale, and the Massachusetts Institute of Technology have found the first evidence that meditation can alter the physical structure of our brains. Brain scans they conducted reveal that experienced meditators boasted increased thickness in parts of the brain that deal with attention and processing sensory input.

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.

“…humans have always been intrigued by the possibilities for influencing mental functioning that emerge from combining rhythmic sound and rhythmic light stimulation. Ancient rituals for entering trance states often involved both rhythmic sounds in the form of drum beats, clapping, or chanting and flickering lights produced by candles, torches, bonfires, or long lines of human bodies passing before the fire and chopping the light into mesmerizing rhythmic flashes. From Greek plays to Western opera, our most popular entertainment forms have made use of combinations of lights and sounds. Some composers, such as the visionary Scriabin, actually created music intended to be experienced in combination with rhythmic light displays.”
Delta brainwaves are slow, loud brainwaves (low frequency and deeply penetrating, like a drum beat). They are generated in deepest meditation and dreamless sleep. Delta waves suspend external awareness and are the source of empathy. Healing and regeneration are stimulated in this state, and that is why deep restorative sleep is so essential to the healing process.
Most of these websites give some brief explanation of entrainment. The example you hear most often is that of Dutch polymath Christiaan Huygens, who in 1665, hung two pendulum clocks next to each other on a wall. He noticed that the pendulums eventually matched each others' frequency, but always in antiphase, opposite to each other, as if canceling each other out. He'd try disturbing one or setting them in sync, but they'd always return to the same antiphase synchronization. Huygen's experience is widely touted on binaural beat websites as a demonstration of how systems can become spiritually connected through some energy field. However, they misunderstand what happened, and have not read the full story. Huygens also tried taking one clock off the wall, and as soon as they were no longer physically connected to one another via the actual wall, the effect disappeared. It was not the proximity of the clocks to one another that created the entrainment; it was their physical, mechanical connection to one another. As each pendulum swung it imparted an infinitesimal equal and opposite reaction to the wall itself. With two clocks on the wall, the system naturally sought the lowest energy level, according to the laws of thermodynamics; and both pendulums would thus swing exactly counter to each other, minimizing the system's total energy.