There are primarily three ways to elicit the frequency following response through an audio: binaural beats, monaural beats, and isochronic tones.  Binaural beats was the first method to be discovered, and has been used since the 80’s, after being first made known and popular by Robert Monroe of the Monroe Institute (the institute is still around today, though Mr. Monroe has passed away).  Binaural beats basically work in this way: one specific frequency/beat is played in one ear, let’s say, 1115 hz., while one slightly different frequency is played in the other at the same time, let’s say, 1120 hz.  What the brain will naturally do while exposed to these two frequencies in either ear is create its own “phantom” beat, that is the difference between the two frequencies.  In this case, it would be 5 hz., which is the frequency of the theta brainwave state.  Therefore, your brain would be led into the theta state.  At the same time, your brain working to combine these frequencies also ends up synchronizing its two hemispheres, and functioning in a whole-brained fashion while the listener is using the audio.
Clinical testing of Brain Sync programs resulted in a record-breaking 87% success rate. They are offered to patients at America's most prestigious hospitals such as Sloan Kettering and Dana Farber Institutes. EEG studies conducted at Harvard Body Mind Medical School, and UCLA concluded that Kelly Howell's Brain Wave Audio Technology® prompts brain activity into extraordinary body-mind states. Vist our Research Findings page for a full list of articles from the Harvard Medical School, the U.S. National Institutes of Health and Psychology Today that concur: the benefits of guided meditation, binaural beats, brainwave entrainment and positive subliminal messaging are real and profound. To learn more see this article about brainwaves in Scientific American.
Blisscoded sound is an invention, or rather a discovery of how to use the golden ratio principle to code sound, giving it properties that has a very strong calming effect on the mind. People use it for meditation, relaxation, sleep and just feeling great. On youtube, the first video I uploaded showcasing the sound has over 9 million views. That is for a reason.
When blended with musical sounds, brainwave entrainment frequencies induce specific states of mind, which are the result of those brainwaves, delivering them in pleasing and relaxing audio tracts for use with and without stereo headphones. For example, alpha and theta waves, because they exist at the borders between conscious and unconscious thought, are especially rich and useful for tapping into and stimulating subconscious processes.
So let’s start with the basics, and we can move on from there. An easier way to understand brainwave entrainment would be to think about how your brain gets entrained in real life, without the use of any technology. Have you ever heard a song on the radio that stuck into your mind throughout the day and maybe even the next one? Now think about a repeating sound, like the ticking of a clock – simply listening to it your brain starts producing alpha waves that match that tick-tack sound. Or have you ever been at a meeting when you immediately felt sleepy? That is because the majority of people in the room were feeling that same way and your brain simply matched the brain wave patterns they have been emanating. We can go on exemplifying this phenomenon, but the main point is that our brain is altering and adapting in direct response to what we hear, think, and see.
Because of the way they are created, there may be a positive benefit from listening to binaural beats without considering the brainwave entrainment aspect, but I haven’t seen any research on that. I first discovered brainwave entrainment through binaural beats about 10 years ago now, but they didn’t do anything for me. So I’ve never been a regular user of them. I believe isochronic tones are a more effective way to produce hemispheric synchronisation because they produce a much stronger response in the brain
While originally brainwave entrainment was achieved by using pure tones of sound, it is now possible to take these tones and blend them with music, rhythms, and natural sounds, such as the sounds of flowing water, bird sounds, or waves lapping on a beach, creating extended tracts of varied and intriguing brainwave entrainment music for everyday use.
The functional role of neural oscillations is still not fully understood;[6] however they have been shown to correlate with emotional responses, motor control, and a number of cognitive functions including information transfer, perception, and memory.[7][8][9] Specifically, neural oscillations, in particular theta activity, are extensively linked to memory function, and coupling between theta and gamma activity is considered to be vital for memory functions, including episodic memory.[10][11][12]