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.
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.  

If mind-consciousness is not the brain, why then does science relate states of consciousness and mental functioning to Brainwave frequencies? And how is it that audio with embedded binaural beats alters brain waves? The first question can be answered in terms of instrumentation. There is no objective way to measure mind or consciousness with an instrument. Mind-consciousness appears to be a field phenomenon which interfaces with the body and the neurological structures of the brain (Hunt, 1995). One cannot measure this field directly with current instrumentation. On the other hand, the electrical potentials of brain waves can be measured and easily quantified. Contemporary science likes things that can be measured and quantified. The problem here lies in oversimplification of the observations. EEG patterns measured on the cortex are the result of electro-neurological activity of the brain. But the brain's electro-neurological activity is not mind-consciousness. EEG measurements then are only an indirect means of assessing the mind-consciousness interface with the neurological structures of the brain. As crude as this may seem, the EEG has been a reliable way for researchers to estimate states of consciousness based on the relative proportions of EEG frequencies. Stated another way, certain EEG patterns have been historically associated with specific states of consciousness. It is reasonable to assume, given the current EEG literature, that if a specific EEG pattern emerges it is probably accompanied by a particular state of consciousness.  
This app offers an easy to use interface that helps you achieve certain states of mind for different activities. From headache treatment to IQ boost to Sleep Induction and Relaxation, this app offers frequencies for over 25 scenarios. If you’re looking for an app that will let you choose a state of mind or activity and then just hit play, this app would be great to use.

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.
However, very experienced practitioners of meditation are able to enter a Delta state and maintain consciousness at the same time. Yoga nidra or “yogi sleep” is a sleep-like state which yogis report during their meditations. This lucid sleeping state is among the deepest possible states of relaxation while still maintaining full consciousness (“super-conscious mind”). In this state, experienced yogis are able to regulate their body temperature and heart rate.
4. Be hesitant committing to any BWE system making wild claims. Profit fueled marketers with little to no experience in the BWE field have created a slew of low-quality entrainment systems on the market. These products typically make outrageous promises such as permanently enhancing the brain within minutes of use. Although BWE is a powerful method to improve the mind, it’s not a magic bullet.
Binaural beats were the first method discovered for brainwave entrainment and works by delivering tones of different audible frequencies to the two ears with the difference in frequency between the two tones being the frequency of entrainment. The difference in frequency between the two tones must be less than 30 hertz, and this resulting frequency is called a beat or the target frequency, and it is processed in a brain region called the olivary body. When listening to such tones with stereo headphones, the two hemispheres of the brain become synchronized at the target frequency.
Neural oscillations are rhythmic or repetitive electrochemical activity in the brain and central nervous system. Such oscillations can be characterized by their frequency, amplitude and phase. Neural tissue can generate oscillatory activity driven by mechanisms within individual neurons, as well as by interactions between them. They may also adjust frequency to synchronize with the periodic vibration of external acoustic or visual stimuli.[3]