Basically, "two ears." One usage of the word is "binaural recording," which is a form of stereo recording meant to take advantage of the spatial perception of the human ear. Recordings are usually done using a pair of microphones mounted to a dummy head with roughly accurate models of the human outer ear, and the result when played back through headphones is extremely realistic and comparable to surround sound, though following an entirely different recording model. Binaural recordings aren't woo at all, and have nothing to do with binaural beats.[citation needed]

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.

There are many ways to reduce tension and relax, but some are more effective than others. Some techniques are difficult to learn while others are challenging to practice. Others have negative consequences that almost outweigh their effectiveness or can create bigger problems. Here are ten stress relievers proven to be among the most effective for the amount of work and time involved. Most can be learned in the time it takes to read this page and will help you to feel more relaxed almost immediately. And even more exciting, the ​stress relief benefits will increase with regular practice. Try as many as you can—there's something here for everyone.
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.

If you happen to be someone who already knows about the physics of sound, then you’ll know that frequencies of 20 hertz or less cannot be heard by the human ear. So how on earth can we use sound to create frequencies as low as 0.1 hertz, and how will you be able to hear them? This is where the “magic” of binaural beats comes into action. Actually, it’s not magic at’s more physics! If you are feeling a bit adventurous, then click on the following link to find out how binaural frequencies are created.
Many people experienced in using alpha brainwave entrainment report that the state of mind associated with alpha waves is a time when they feel most consciously connected to their subconscious mind. The intense experience of hypnagogic sleep, reported by some people as a feeling of being awake and asleep at the same time, is also associated with alpha brainwaves.
For our ancestors, stress was a survival skill during brief, life threatening situations. Once the danger passed, their stress levels lowered. However, in today’s world, we are constantly bombarded by stressors, such as work deadlines, traffic, and family obligations. We rarely get a break long enough to relax and relieve the stress. The over-activation of our stress hormones have been linked to high blood pressure, heart attacks, lower immunity, depression, anxiety, and more.
Your brain operates at certain levels of activity – the normal waking, active Beta, the meditative Alpha, the asleep-and-dreaming or deep meditative Theta, and the deep sleep/unconscious Delta. Beta is characterized by one thing we all want to get away from – stress.But that brainwave state has its place. It’s the action mode, and that’s the way it should be! If we’re not alert when we’re awake, bad things can happen, right?
These are just a few examples. This silly list literally goes on for pages and pages, and it is pure hogwash almost without exception. Unfortunately there are many people dealing with personal problems that read nonsense like this and want very badly for it to be true. Perhaps they don’t believe every word, but they believe or hope that at least some of it is accurate information. These hopes and beliefs contribute to the generation of false expectations, so that when listening to an entrainment frequency of 10.3Hz doesn’t clear up their stuffy sinuses they conclude entrainment doesn’t work. The digestion of such foolishness is an impediment to realizing the true value of entrainment.

This incredible app which you  not only has over 3 hours of meditations valued at $200, the technology utilized is unlike anything else on the marketplace. The heartbeat synchronization augmentation gives you a completely immersive experiencing, tuning in to your body’s natural rhythms. It gives you the best binaural music on the market. Fully customizable, you can base your meditation on your mood, goals and timeframe. This is the perfect app for a deep, introspective experience.
It might seem obvious that you’€™d know when you’€™re stressed, but many of us spend so much time in a frazzled state that we’ve forgotten what it feels like when our nervous systems are in balance: €”when we’€™re calm yet still alert and focused. If this is you, you can recognize when you’re stressed by listening to your body. When you’re tired, your eyes feel heavy and you might rest your head on your hand. When you’re happy, you laugh easily. And when you’re stressed, your body lets you know that, too. Get in the habit of paying attention to your body’€™s clues.
In addition to the exercise prescription, other characteristics of the exercise session (e.g., group vs. individual) and the individual also are important considerations. Because of health consequences associated with stress, high-stress clients are likely to be at increased risk for cardiovascular disease and cardiovascular events during exercise. Therefore, using the preexercise screening procedures outlined and endorsed by the American College of Sports Medicine is essential (1). Monitoring exercise intensity for those looking to “blow off steam” to reduce stress might be a concern when the client has high blood pressure or other cardiovascular risk factors that further the risk increase for cardiovascular events.
When you play two separate frequencies in each ear, say 140 Hz and 149 Hz, the difference in frequency is 9 Hz. Your brain compensates for this difference and a third tone of 9 Hz is experienced. This will result in your brain being lowered or raised and tuned into the desired frequency. This is how binaural beats are produced. Headphones are essential for this to work.  
Let’s face it, the stress we face today isn’t going anywhere, which is exactly why it’s more important than ever to find natural ways to bust stress that work well for us. If you’re up against large amounts of stress in your life (and who isn’t?), studies show you can greatly benefit from carving out more time in your busy schedule for things like regular exercise, meditation, spending time outdoors and keeping up with fun hobbies.
With brain wave entrainment technology, changing brain wave states is an instantaneous and effortless process. The 'periodic stimulus' can be sound, vibrations and/or light. We have found that we get the best results with blinking lights which are experienced through closed eyelids. This is only problematic for people with existing diagnosis of photo-induced epilepsy, as blinking lights can induce a seizure in them. The programs are enhanced with Deepak Chopra doing the narration along with holographic sound effects and original music composed and performed by Rudy Tanzi.
Resonant entrainment of oscillating systems is a well-understood principle within the physical sciences. If a tuning fork designed to produce a frequency of 440 Hz is struck (causing it to oscillate) and then brought into the vicinity of another 440 Hz tuning fork, the second tuning fork will begin to oscillate. The first tuning fork is said to have entrained the second or caused it to resonate. The physics of entrainment apply to bio-systems as well. Of interest here are the electromagnetic brain waves. The electrochemical activity of the brain results in the production of electromagnetic wave forms which can be objectively measured with sensitive equipment. Brain waves change frequencies based on neural activity within the brain. Because neural activity is electrochemical, brain function can be modified through the introduction of specific chemicals (drugs), by altering the brain's electromagnetic environment through induction, or through resonant entrainment techniques.

This is probably the most popular choice of frequency. The theta state is a state of tremendous stress relief. The benefits associated with theta level relaxation include improved concentration, reduced hyperactivity and improved memory. While in a state of theta relaxation, one’s blood pressure, breathing and heart rate all slow to a much more restful and healthy level that promotes natural healing. During theta relaxation one may also experience vivid flashes of mental imagery as the mind opens to memories or subconscious information that is not available to the conscious mind during the normal waking state. The theta state is a very deep state of relaxation that is excellent for deep hypnosis and mental programming.
Cortisol is the principle hormone (although not the only hormone) tied to our innate “flight-or-fight” response, which is how the body reacts to acute stress by either helping us run from the situation or stick around and fight our way through. When short spikes in cortisol/adrenaline happen over and over again nearly every day, they cause wear and tear on the body and speed up the aging process.

How does brainwave entrainment work? Consistent, precisely engineered audio frequencies in the form of binaural beats cause the brain’s frequencies to match the stimulus. Your brain perceives two beats with slightly different frequencies (which are inaudible to the ear) through your headphones. It takes the difference between the two, and matches its own frequency to it. This is called the “frequency following” response.