If you’re going to enter a state of meditation, a technique of some sort must be employed that takes you there. (Note – I am fully aware of references to “spontaneous enlightenment experiences”, but these are an entirely different category of phenomena than what is being discussed here and are outside the scope of this discussion. Perhaps another time.)
The most common way to use a brainwave entrainment is for a short-term benefit, to help guide your brain into a particular mental state at the time you need it.  In a similar way to how you might take a sleeping pill before bed to help you get to sleep, or maybe drink some coffee or an energy drink to help wake you up and give you a boost of energy.
These sounds in these musical tracks are presented through monaural beats, binaural beats, isochronic tones, or a mixture involving combinations of all three of these modalities, described in detail below. Choose alpha brainwave tracks for calming anxiety and relaxing body and mind, and choose theta tracks for help in getting to sleep and for bringing hidden feelings to the surface. Some people also report out-of-body type experiences when in theta brainwave states.
Move your focus to the sole of your right foot. Tune in to any sensations you feel in that part of your body and imagine each breath flowing from the sole of your foot. After one or two minutes, move your focus to your right ankle and repeat. Move to your calf, knee, thigh, hip, and then repeat the sequence for your left leg. From there, move up the torso, through the lower back and abdomen, the upper back and chest, and the shoulders. Pay close attention to any area of the body that causes you pain or discomfort.
Brainwave entrainment is a simple concept. It’s simply causing your brainwave frequency to align with some intended frequency in order to produce some intended result. It’s a way of modulating your brainwaves to resonate at a certain frequency. Being that there are certain dominant frequencies associated with different states of consciousness, this is being researched as a quick and effective way to induce states such as sleep, alertness, concentration, and even meditative and deep sleep states.
Your brain cells reset their sodium & potassium ratios when the brain is in Theta state. The sodium & potassium levels are involved in osmosis which is the chemical process that transports chemicals into and out of your brain cells. After an extended period in the Beta state the ratio between potassium and sodium is out of balance. This the main cause of what is known as "mental fatigue". A brief period in Theta (about 5 - 15min) can restore the ratio to normal resulting in mental refreshment.  
The pitch frequency measures and describes what a beat sounds like, i.e. does the isochronic beat have a deeper bass sound, or is it high pitched and sharper sounding? The beat waveform frequency describes how many times the beat is repeating per second, i.e. how fast it is beating. You don’t really need to concern yourself about the pitch frequency, as that doesn’t have a direct influence on brainwave entrainment and doesn’t play a part on the measurement on an EEG. I only mentioned it because you were referring to humans not being able to hear below 20Hz. I change the pitch frequency just to suit the mood of the track. For tracks that are to be relaxing, for meditation or sleep, I tend to use a lower pitch frequency so it sounds deeper and more relaxing and I never have that lower than 100Hz. For an energizing, high focus track I might use a more higher pitched 200Hz isochronic tone, because that is sharper sounding and less likely to make you feel sleepy. That’s all you really need to know about the pitch frequency.
I am very encouraged by my stroke recovery progress after starting with Sacred Acoustics! I have been listening to the extended Light Body (non verbal) recording almost constantly. I keep it on the repeat mode and at a low enough volume so that I do fine with ordinary conversation as I go about my daily activity. The results with constant listening of Light Body are so fantastic, I hate to stop! 
♥ I admit that I do not know much about brainwaves and can be swayed by suggestion (ah, the fickle subconscious), but since using this machine and sort of hiding the noise with other sounds or my own music so it is not so obvious to me, it has helped me get through my email correspondences and other online tasks with the focus that I need. Thank you so much for making this!
Binaural beats must be listened to using headphones. You definitely should not use them while driving or operating heavy machinery as you will be in an altered state of mind. Brainwave entrainment is a form of meditation and designed to be very passive, in fact, all you need to do is sit back, put on your headphones and let the technology do the work for you. It is best to find a session that you find soothing to listen to, as binaural beats on their own are a very strange sound that can be disturbing to some listeners. This was actually what inspired me to invent Trypnaural as a way for brainwave entrainment to be more bearable to listen to for long periods of time.
This music encourages a state of delta relaxation. Delta brainwaves are most prevalent during deep, dreamless sleep. The delta state is a mostly unconscious state that is essential to one’s physical, emotional, psychological and spiritual wellbeing. People who are able to achieve a state of delta relaxation through meditation will sometimes describe spiritual encounters and out of body experiences. The delta state is perfect for inducing profound spiritual experiences, healing and deep subconscious repatterning. Delta frequency brainwave entrainment music is also a fantastic cure for insomnia.

These tones are similar in that they pulse like binaural beats. The difference is that they don’t need to be listened to using headphones as the pulse, or beat, is not generated by two different frequencies. The sound is an on/off pulse. Although you don’t need headphones to seperate the frequencies listened to, they are recommended. I’ve had just as much response to isochronic tones as I’ve had to binaural beats. I’d try both though, especially if you don’t respond to one or the other.

All brainwave frequencies are useful and beneficial at certain times – there is no brainwave that is intrinsically better than another. However, by deliberately choosing to attain a particular brainwave state, a corresponding mental state can be brought about at the same time. For example, a working person who has been in an overly alert beta brainwave pattern for many hours can quickly shift their mind and body into a relaxed state by listening to a few minutes of brainwave entrainment music for inducing alpha or theta brainwaves.
Set aside time in your daily schedule. If possible, schedule a set time once or twice a day for your practice. If your schedule is already packed, remember that many relaxation techniques can be practiced while performing other tasks. Try meditating while commuting on the bus or train, taking a yoga or tai chi break at lunchtime, or practicing mindful walking while exercising your dog.
Using a small amount of alcohol in the Pregnancy and Children's lines was a conscious decision. It enables us to keep the strength and efficaciousness of the formula intact but is also gentle and appropriate for women and children. Extracts made with only glycerine or water limit the constituent profile. WishGarden's finished extract contains a minimal amount of alcohol, which, per serving, is at a very low dietary level (similar to what is found in kombucha and ripe bananas). You can also further reduce the alcohol content by stirring your droppers full, or pumps, into hot water or tea for a few minutes.
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]