When tuning instruments that can produce sustained tones, beats can be readily recognized. Tuning two tones to a unison will present a peculiar effect: when the two tones are close in pitch but not identical, the difference in frequency generates the beating. The volume varies like in a tremolo as the sounds alternately interfere constructively and destructively. As the two tones gradually approach unison, the beating slows down and may become so slow as to be imperceptible. As the two tones get further apart, their beat frequency starts to approach the range of human pitch perception[1], the beating starts to sound like a note, and a combination tone is produced. This combination tone can also be referred to as a missing fundamental, as the beat frequency of any two tones is equivalent to the frequency of their implied fundamental frequency.
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.

Maybe a favorite popular song, a certain piece of Classical music, a raucous dance beat, the pulse of Reggae, Indian, or African drums, or the chanting of Gregorian or Tibetan monks, but you probably know how the sound of music, drumming, or chanting is capable of transporting you into an altered and joyous state of mind and uplifting your spirits.
Delta is the lowest frequency range of .2Hz - 3Hz, corresponding to dreamless sleep, growth hormone release, healing and ultra deep trance. Effective in reducing migraines, chronic pain and blood pressure. By inducing a predominantly Delta state in the brain while remaining awake, you push your brain to operate in a truly unique state that literally forces greater neural adaptation and cross-connection between the regions of your brain.
It may be that you had the volume too loud, but I would expect you to hear the effects of that straight after you’ve stopped listening, not on a day you haven’t used them. It might be something similar to muscle memory, where you suddenly remembered the sound and sensations it gives you as if you were hearing it again. I don’t know how long you’ve been using this type of thing for, but maybe it’s something that will settle down and disappear once you become more accustomed to the sound.
According to an American Psychological Association (APA) survey, more women than men (one in three) turn to comfort food such as ice cream and cookies to ease stress. It's common for women to deny themselves favorite foods because they're trying to lose weight. But under stress, the urge for them becomes even stronger. In fact, researchers at Montclair State University in New Jersey recently confirmed that dieters are more likely than non-dieters to overeat when under pressure, bingeing on the very same high-fat foods they normally try to avoid. The key is to not deprive yourself. Keep three or four healthy snacks on hand that you know you'll probably want--peanuts, if you like salty; string cheese, if you crave protein; a small piece of chocolate for something sweet--so you aren't tempted to binge.

Thanks for the reply. I am now clearer on ‘what’ is heard. Can you expand or point me in direction ..a bit more about ‘pitch frequency’ and frequency spoken about and what exactly is the difference ..and how we use the higher pitch frequencies to ‘hear’ or become aware of them? Would you only pick up the low freq on a EEG?. sorry for being pedantic ..it still does not clear up split isochronics and possibly creating same situation as binaural beats..
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.  
Nothing is more stressful than being unprepared. Get organized so you're ready for the next day, taking a few minutes to make a to-do list and clean up before you leave. Knowing you've got everything covered means you'll be less likely to fret about work in the evenings. When you come in the next morning, you'll have the sense that you're in control of the situation and can handle it. This sets a positive tone for the day, which can help you get more accomplished. (You can even turn your nightly beauty routine into a stress-relieving practice.)
Thanks to e-mail, cell phones, and BlackBerrys, it seems like your job never ends. The increasingly blurry boundaries between work and home life leave us with less downtime than ever before (and in some cases, no downtime!). Advances in technology are a leading source of chronic stress, putting many of us in a constant state of alert. Not to mention the effect it has on family ties. A recent study published in the Journal of Marriage and Family found a link between the use of cell phones and pagers at home and increased stress, which spills over into family life. To make technology work for you, screen calls with caller ID or, better yet, limit your cell phone and e-mail use to working hours only. Can't kick the BlackBerry habit? Set a regular time you'll check it in the evening (say, after dinner), so you're not constantly disrupting home life to keep tabs on work. (The one exception: using your device to breathe with this anxiety-reducing GIF.)
Slumping can be an outward sign of stress—not to mention that bad posture actually puts more physical stress on your body. “People who are overly stressed often display their worries in their body carriage,” Whitaker says. “Those who are weighed down with stress commonly have a poor posture or struggle with aches and pains in their body. They often slouch when sitting or concave their body inwards with rounded shoulders as they go about their business under the weight of the burdens they carry.” Taking a few seconds when you feel stressed to check your posture and sit up straight (like your mother told you) can help you feel better. “Studies show that poor posture is related to anxiety, depression, helplessness, and irritability, so keeping your chin up and shoulders back will help,” Dr. Serani says. Happy and confident people naturally tend to stand a bit taller. Here are the other stressors you didn’t know you had.

Brainwaves, or neural oscillations, share the fundamental constituents with acoustic and optical waves, including frequency, amplitude and periodicity. Consequently, Huygens' discovery precipitated inquiry[citation needed] into whether or not the synchronous electrical activity of cortical neural ensembles might not only alter in response to external acoustic or optical stimuli but also entrain or synchronize their frequency to that of a specific stimulus.[16][17][18][19]