For example, according to Wikipedia, if you take one frequency in one speaker in a pair of headphones, say, 300Hz, and the other speaker for your other ear has a frequency of 310Hz, the resulting difference of 10Hz would be the rate that the pulse, or beat, plays at. 10Hz (Alpha Waves) would correspond to what the brain puts out when you are generally relaxed. So, in effect, listening to a 10Hz binaural beat for a certain amount of time should take the edge off.
That is generally where the science ends and the pseudoscience begins. A number of companies and individuals have then extrapolated from the phenomenon of entrainment to claim that altering the brain waves changes the actual functioning of the brain. There is no theoretical or empirical basis for this, however. Entrainment is a temporary effect on the synchronization of neuronal firing – it does not improve or increase brain functioning, it does not change the hardwiring, nor does it cure any neurological disorder. There is no compelling evidence for any effect beyond the period of entrainment itself.
Gaia Meditation Gamma programs are specifically designed to: stimulate cognitive functions, help for higher learning and greater focus, improve IQ, expand consciousness and inspiration. The Dalai Lama meditates 4 hours every morning, which must stimulate his Gamma activity in a tremendous way. However, even if you have never practiced meditation, our Gamma waves programs will take you easily and rapidly to the Gamma brain state.

With digital upgrades, Berger’s machine is still in use today, known as an electroencephalography machine, or EEG. Berger used his machine to study the brains of psychologically normal and abnormal people and discovered the first brainwave, called the alpha wave and also known as the Berger wave, along with the faster beta wave, which he observed suppressing the alpha wave when subjects opened their closed eyes. 
Your brain actually has a predominant frequency at which it operates in any given moment; this can be associated with your state of mind. In other words, the emotional state of your mind in any moment, such as feeling happy, sad, frightened, sleepy or excited, can be measured as a frequency and with the right sound technology, you can stimulate the state that you want on command!
However, with this integration will come upheavals as the mind is forced to integrate areas of the brain that were previously sequestered. Repressed memories and unpleasant emotions from the past will often rise to the surface of the mind to be processed and healed. This is sometimes referred to as "processing the shadow" within one's mind and emotions.
If new stressors are challenging your ability to cope or if self-care measures just aren't relieving your stress, you may need to look for reinforcements in the form of therapy or counseling. Therapy also may be a good idea if you feel overwhelmed or trapped, if you worry excessively, or if you have trouble carrying out daily routines or meeting responsibilities at work, home or school.
Cortisol is an arousal hormone, stimulating alertness and attention. Cortisol levels rise and fall in connection to circadian rhythms—cortisol levels rise to their peak levels first thing in the morning, just in time for you to be active for the day. Too-high cortisol levels are associated with insomnia, as well as more time spent in light sleep, rather than deep sleep.
Each of us is unique, and what works well for me might be totally useless to you. Generically speaking, there are three types of meditation techniques. There are techniques that take your awareness outwards, techniques that take your awareness inwards, and techniques that do a little of both. People with exceptionally busy minds tend to do better with techniques that take awareness outwards since their minds naturally head that direction anyway. People with more contemplative natures tend to do better with techniques that take you inwards. The combination techniques are a “maybe” for just about anyone, but are usually best used when a person has some experience with meditation under their belt.
The heart meditation is amazing. The recording of sound, vibration and guided words were heartfelt. I felt energy in waves as I listened and felt various sensations of heat, tingling, and muscular tension release as I become one with the recording.  A sincere thank you for making these recordings available to us in search of an enlightened path with the help of sound and vibration. 

From a brainwave entrainment effectiveness perspective, it’s my understanding that the response from isochronic tones stimulation starts to diminish over 30Hz and that 40Hz is about the limit for using them. So from what I’ve read on the topic a 100Hz beat wouldn’t work, probably because it’s too fast for the brain to process and synchronise with it.

Both brainwave entrainment and neurofeedback deal with brainwaves, but the similarity stops there. Entrainment pushes your whole brain into a pre-determined state, while neurofeedback teaches you how to move specific parts of your brain on your own. It is the differeence between forcing the brain into a given position, and skills building so you can move it there yourself.