At any one moment, the human brain contains thousands of different brainwaves which are produced by the electrical signals transmitted between the billions of neurons from which the brain is constructed. Through the use of specialized equipment, such as an EEG (electroencephalography) it is possible to see and record all brainwave activity, which then allows for the brainwaves to be analysed and monitored. EEG recordings show that brainwaves change depending upon the activity of the monitored individual.

History

First discovered by biophysicist Gerald Oster at Mount Sinai Hospital in New York City, Brainwave Therapy sends pure, precisely tuned sound waves of different frequencies to your brain via stereo headphones. In his EEG research, Oster discovered that when different vibrations, or sound frequencies, are delivered to the brain separately through each ear (as with stereo headphones), the two hemispheres of the brain function together to “hear” not the external sound signals, but a third phantom signal. This signal is called a binaural beat, and it pulses at the exact mathematical difference between the two actual tones. For example, a signal of 100 Hz delivered to the left ear and a signal of 107 Hz delivered to the right creates a binaural beat of 7 Hz which in this case falls into the Alpha range.

Brainwave groups

There are many forms of brainwaves, but in essence they can be grouped into four distinct categories, each of which represents a different mental state. The four most recognized groups of brainwaves are; Alpha, Beta, Theta and Delta.
Alpha frequency
Alpha brainwaves are generated by the brain when in a relaxed but alert state. As discussed in another article here, each group carries a particular frequency, the alpha range is 8hz to 14hz. Alpha is generally a very desired frequency, and has many uses in terms of brain entrainment. It is a target frequency for many meditators, and is also very effective in reducing stress, anxiety and nervousness.
Beta frequency
At a frequency between 14hz and 30hz, beta brainwaves are the most dominant during times of high mental and physical activity. Stimulating beta brainwaves can lead to higher levels of concentration, improving learning ability and attention. Research into ADD and ADHD has also confirmed that increasing beta levels can be of benefit to those with that condition.
Theta frequency
Found during periods of dreaming, trance and hypnosis, theta brainwaves operate at a frequency of 4hz to 8hz. Theta is also used during entrainment to induce high levels of relaxation, and deep meditations. At low theta levels, the pineal gland can become stimulated which in turn can bring on mild visions, as well as enhance intuition and imagination.
Delta frequency
Associated with deep sleep, delta brainwaves are found between the frequencies of 0.5hz and 4hz. Delta entrainment is most regularly used to induce sleep and is actually a recognized aid for helping with insomnia. Individuals who are exceptionally skilled with meditation can sometimes attain delta brainwaves whilst remaining awake.

If you’ve never listened to any binaural beats or are just trying out brainwave programs which allow you to choose different frequencies, it’s a good idea to slowly reduce the frequency a little at a time, from Beta to Alpha and so on.
Don’t be too ambitious and immediately set a binaural beat of 4Hz, down from your normal Beta brainwave frequency of 14 plus Hz. If you do, you’re going to find it extremely uncomfortable.
It’ll be difficult for your mind to process all that energy without even having gone through Alpha state (7-14 Hz). What’s happening here is that each time you entrain your brain waves to a new lower frequency, your mind is building new neural pathways through your brain.
Each time you listen to a frequency, the neural pathways are strengthened as your mind and body physically adjust itself to the lower frequency.
It’s like training for a race. If you’re not fit enough to run a 100-yards race, it’s not likely that you’ll be able to immediately run a marathon.