Most wisdom traditions have employed methods that allow the subjects' brain waves to slow down such as meditation, [Hindu] kirtan, [Gregorian, Menzuma or Sufi] chanting, Hebrew davening, Native American drum circles and rain chants, Tibetan prayer bowls, and whirling dervishes and African trance dancing. The rhythm of these wisdom tradition technologies actually slows people's brain waves from their normal busy brain frequency we call Beta (13-30 cycles per second or Hz), to Alpha (8-13Hz) -- meditation, Theta (4-8Hz) -- deep relaxation and dreaming, and Delta (.5-4Hz) -- slow wave or dreamless sleep.

Because the brain filters and interprets reality in a split-brained way, we tend to see things as separate and opposed, rather than as connected and part of the oneness spoken of by the great spiritual teachers (and, in the last few decades, by quantum mechanical physicists). Thus, at a deep level, the dual structure of our brain, in conjunction with brain lateralization, predisposes us to see and experience ourselves as separate from, and often in opposition to, the rest of the world—instead of experiencing the elegant interconnectedness between us and everything else. Our childhood associations and programming build on this inborn tendency by training us to seek this and avoid that, to move toward pleasure and away from pain, to do good and not bad, and so on. The greater the lateralization in the brain, the greater the feelings of separation—and the greater the feelings of separation, the greater the fear, stress, anxiety, and isolation.

Recent research at the University of Lisbon finally uncovered the reason for the 350 year-old mystery, finding that the resonance of sound is the mechanism for entrainment of swinging pendulums and ticking clocks, and it seems likely that the energy transferred by sound is also responsible for other observations of entrainment, including brainwave entrainment.
These brainwaves are actually a bit of a mystery. They’re the highest frequency you can achieve, but scientists are a little dumbfounded by them. Unlike the next set of brainwaves (Alpha and Beta), Gamma brainwaves don’t’ really translate to feeling active and alert. Rather, what’s been discovered is that in Gamma, neurons are firing so harmoniously, that people often feel like they are having a spiritual experience. This brainwave state has been associated with expanding consciousness and understanding the value of universal love and harmony.
Some research suggests that the benefits from brainwave entrainment can last a lot longer, and still be seen for some time after you've stopped using it.  Study participants have still maintained improved test scores a few weeks after the stimulation had ceased.  Research on the long-term benefits has so far been minimal though, so how long the effects last is still up for debate.
... Several studies have looked at the possible effects of binaural beats within the alpha range on cognitive abilities. A significant improvement in cognitive processing, as measured by the Stroop Effect exercise, was found by a BB stimulation of 10.2 Hz frequency (Cruceanu & Rotarescu, 2013).Carter and Russell (1993)exposed 8 to 12 year old boys with learning disabilities to 8-week long 10 and 18 Hz BB stimulation sessions, and they found an improvement in Raven's progressive matrices and in a subtest of auditory sequential memory (Carter & Russell, 1993).McMurray (2006)assessed the effect of 7 and 11 Hz BB on alpha brainwave activity, working memory, and attention in healthy elderly people, who are known for experiencing gradual decrease in physiological alpha activity. The 2 minutes exposure to BB resulted in an altered electrical activity in the brain. ...
A study published in Electroencephalography and Clinical Neurophysiology by Paul Williams and Michael West in 1975 examined the brainwave states of people experienced in meditation while using photic stimulation, and another study by Leonard, Telch, and Harrington in 1999 examined the successful use of brainwave entrainment techniques for attaining meditative states in subjects.
“A quite different phenomenon results when stereophonic earphones are used and the signals are applied separately to each ear. Under the right circumstances beats can be perceived, but they are of an entirely different character. They are called binaural beats. . . . Binaural beats require the combined action of both ears. They exist as a consequence of the interaction of perceptions within the brain.”

However, by listening to binaural music you can dramatically accelerate your progress with meditation, and achieve a far deeper, more relaxing state of mind than you would by practicing traditional meditation techniques. In fact, almost everyone discovers that uses binaural meditation music finds that they go deeper into meditation, faster, and with less concerted effort.
Escape from a stressful situation by remembering a favorite vacation spot or a place where you feel cozy and at home. “Make sure to take note of every detail of your favorite spot—the more detailed your visualization, the more stress gets kicked to the curb,” Dr. Serani says. “For me, it’s a beautiful spot on the beach in my native Long Island. But it’s not just the white velvet sand of the beach or the teal blue ocean water; it’s the sounds of the surf, the tang of the salt water, the feel of the sun, the waves in the distance, and the imagined walk I take along the water.” You can combine this with a three-word mantra like “blue-ocean-water,” Serani suggests. Miller calls the visualization of a memory that evokes a positive association an “anchor.” She remembers watching beautiful sunsets in Costa Rica. “Now that I am back in the hustle and bustle of life, I will often pause and take mini-retreats, bringing up the anchored experience of inner calm that I felt watching the sunsets,” she says.
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.
So using the example track above, the right ear is sent a 20Hz beat, compared to a 10Hz beat in the left ear.  As the right ear receives the higher frequency of beat, this works to increase the speed of the ‘left' brain hemisphere, which can be helpful for people with conditions like ADD, who are often found to have an abundance of slow wave activity in the left brain.
Respectfully ask others to change their behavior. And be willing to do the same. Small problems often create larger ones if they aren't resolved. If you're tired of being the target of a friend's jokes at parties, ask him or her to leave you out of the comedy routine. In return, be willing to enjoy his or her other jokes and thank him or her for humoring you.
There is no single relaxation technique that is best for everyone. The right relaxation technique is the one that resonates with you, fits your lifestyle, and is able to focus your mind and interrupt your everyday thoughts to elicit the relaxation response. You may even find that alternating or combining different techniques provides the best results. How you react to stress may also influence the relaxation technique that works best for you:
Given that brainwaves control and connect such a vast range of human experience from thought to feelings to actions, it is easy to see how the deliberate control of brainwaves can affect mood, behaviors, motivation, and even physical health. Brainwave entrainment is a safe, simple, and scientifically proven method for quickly guiding the brain into a beneficial brainwave frequency to facilitate healthy sleep, lower stress, heal emotional problems, and improve physical health.
For example, if a 530 Hz pure tone is presented to a subject's right ear, while a 520 Hz pure tone is presented to the subject's left ear, the listener will perceive the auditory illusion of a third tone, in addition to the two pure-tones presented to each ear. The third sound is called a binaural beat, and in this example would have a perceived pitch correlating to a frequency of 10 Hz, that being the difference between the 530 Hz and 520 Hz pure tones presented to each ear.
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“.

A binaureal beat is created by playing a different tone in each ear, and the interference pattern between the slightly differing frequencies creates the illusion of a beat. It's intended to be heard through headphones, so there's no cross-channel bleed across both ears. Listen to this, I'll play a simple binaural beat, and I'll slide the pan control back and forth from one ear to the other. You can see that there isn't actually any beat, it's just an acoustic illusion:
♥ Imagine a really bad ringing in your ear and the pain that it brought along or when your ear was throbbing with pain. Can you remember the sound coming from that ear? Probably not, since the pain was probably far more memorable. This sounds very similar to that, but it is not at all painful. Quite a unique experience, really. Try it out, but you need to be wearing earphones and have the volume up.

When you hit a tuning fork, tuned to a particular sound frequency such as the note B, and hold it close to the strings of a guitar, you will notice that the B string on the guitar will vibrate because it has entrained on to the same frequency of the tuning fork. Interesting enough, the other strings will not vibrate. Only the one with the same tuning as the tuning fork.

However, yoga and meditation take time to learn and master, and until the student becomes proficient, progress can be slow and frustrating, leading many people to abandon the effort before they see the benefits. Brainwave entrainment has the potential for helping a person enter the relaxing and rejuvenating mind-states brought about by yoga and meditation without the learning curve and time needed for mastering these other techniques. Brainwave entrainment may even facilitate learning other mindfulness methods by helping a person achieve success faster and more reliably. 
Binaural beats were discovered in 1839 by a German experimenter, H. W. Dove. The human ability to "hear" binaural beats appears to be the result of evolutionary adaptation. Many evolved species can detect binaural beats because of their brain structure. The frequencies at which binaural beats can be detected change depending upon the size of the species' cranium. In the human, binaural beats can be detected when carrier waves are below approximately 1000 Hz (Oster, 1973). Below 1000 Hz the wave length of the signal is longer than the diameter of the human skull. Thus, signals below 1000 Hz curve around the skull by diffraction. The same effect can be observed with radio wave propagation. Lower-frequency (longer wave length) radio waves (such as AM radio) travel around the earth over and in between mountains and structures. Higher-frequency (shorter wave length) radio waves (such as FM radio, TV, and microwaves) travel in a straight line and can't curve around the earth. Mountains and structures block these high-frequency signals. Because frequencies below 1000 Hz curve around the skull, incoming signals below 1000 Hz are heard by both ears. But due to the distance between the ears, the brain "hears" the inputs from the ears as out of phase with each other. As the sound wave passes around the skull, each ear gets a different portion of the wave. It is this waveform phase difference that allows for accurate location of sounds below 1000 Hz(9). Audio direction finding at higher frequencies is less accurate than it is for frequencies below 1000 Hz. At 8000 Hz the pinna (external ear) becomes effective as an aid to localization. In summary it's the ability of the brain to detect a waveform phase difference is what enables it to perceive binaural beats.
If you search the Internet for "binaural beats" you'll quickly find there's a whole industry built on the idea that listening to binaural beats can produce all kinds of desired effects in your brain. It can alter your mood, help you follow a diet or stop smoking, get you pumped up for a competition, calm you down, put you to sleep, enhance your memory, act as an aphrodisiac, cure headaches, and even balance your chakra. Binaural-Beats.com offers a $30 CD that they call the world's first "digital drug". They claim it can get you drunk without the side effects. I-Doser.com offers a range of music tracks that they say simulates a variety of actual pharmaceuticals, such as Demerol, Oxycontin, and Vicodin. Suffice it to say that no matter what superpower you're looking for, someone on the Internet sells a binaural beat audio file claimed to provide it.
Born in California, TYLER SUSSMAN attended the University of California, Santa Barbara and studied psychology in addition to music. He became fascinated with the mind/body connection and music's impact on the psyche. Tyler moved to New York City in 2008 and founded the Didge Project in collaboration with AJ Block. In 2009, Tyler produced the brainwave entrainment recording entitled “Didgeridoo Meditation: An Odyssey through Consciousness." In 2011, Didge Project released an jazz/world fusion of original music entitled "As One." Tyler's self titled original music debut with his own band "WawaAlchemy" was released in 2014. Tyler has created soundscapes in collaboration with yoga teachers in since 2008 and has performed at Wanderlust Festivals in California, Vermont and Oahu. Tyler works extensively with vocalist Aya creating soundscapes for yoga and meditation. Aya and Tyler released a record entitled "Oshuns of Love" in 2015 and host a weekly Sacred Soundbath Meditation at ISHTA Yoga NYC. Tyler currently resides in Brooklyn, NY.
Maya Mendoza is a published author of 3 personal development books. She has run an NLP / EFT Practice for 29 years helping clients transform problems into personal power. Maya is also a accomplished copywriter and well known Digital Marketing & Social Social Media Strategist - Specializing in Google+ for business. She was named "best marketing consultant" in Glasgow, UK in 2013.  
A potential and generally desired result of brainwave entrainment is hemispheric synchronization. It refers to a state when the brainwave pattern of the right and left hemispheres become alike. It is said that a person with similar activity in both hemispheres tend to be happier, more optimistic and more emotionally stable and less prone to mental illness. Studies found that increased levels of synchronization are found naturally in people who meditate regularly and people who are very happy with their lives in general.
Stress affects your whole body, so find a pick-me-up for each of your senses. Turning on a favorite tune uses your sense of hearing for a science-backed burst of good feeling, and using aromatherapy uses your sense of smell to relax you. “Oils like lavender and lemon reduce stress,” Dr. Serani says. “Also, don’t forget that your sense of smell is the most nostalgic of all your senses,” so if you have a scent that reminds you of comfort, keep it on hand to sniff when you’re freaking out. Your sense of touch can be employed by stroking a “talisman”—a favorite or sentimental item—or even an “intention stick,” which you can hold like a wand to feel more in control. Chew gum to use your sense of taste to curb stress (scientists think it’s the lasting flavor, not just the act of chewing itself, that makes gum such a great stress reliever). Besides using your mind’s eye to visualize a happy place, you can use your sense of sight to look at calming images—cat videos on the Internet have actually been scientifically proven to lower stress.
Now I’m in the market for two extra tracks to have some variety. I have narrowed it down to a couple of ones including muscle relaxation which is theta and delta. I have a hard time relaxing my body. The last time my muscles where relaxed was after intensely cleaning my stove. I don’t want to clean every time I want to relax, even though my house will be spotless ;).
Both brainwave entrainment and neurofeedback deal with brainwaves, but the similarity stops there. Entrainment pushes your whole brain into a pre-determined state, while neurofeedback teaches you how to move specific parts of your brain on your own. It is the differeence between forcing the brain into a given position, and skills building so you can move it there yourself. 
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