Most of these websites give some brief explanation of entrainment. The example you hear most often is that of Dutch polymath Christiaan Huygens, who in 1665, hung two pendulum clocks next to each other on a wall. He noticed that the pendulums eventually matched each others' frequency, but always in antiphase, opposite to each other, as if canceling each other out. He'd try disturbing one or setting them in sync, but they'd always return to the same antiphase synchronization. Huygen's experience is widely touted on binaural beat websites as a demonstration of how systems can become spiritually connected through some energy field. However, they misunderstand what happened, and have not read the full story. Huygens also tried taking one clock off the wall, and as soon as they were no longer physically connected to one another via the actual wall, the effect disappeared. It was not the proximity of the clocks to one another that created the entrainment; it was their physical, mechanical connection to one another. As each pendulum swung it imparted an infinitesimal equal and opposite reaction to the wall itself. With two clocks on the wall, the system naturally sought the lowest energy level, according to the laws of thermodynamics; and both pendulums would thus swing exactly counter to each other, minimizing the system's total energy.

You can practice visualization on your own or with a therapist (or an app or audio download of a therapist) guiding you through the imagery. You can also choose to do your visualization in silence or use listening aids, such as soothing music or a sound machine or a recording that matches your chosen setting: €”the sound of ocean waves if you’ve chosen a beach, for example.
Resonant entrainment of oscillating systems is a well-understood principle within the physical sciences. If a tuning fork designed to produce a frequency of 440 Hz is struck (causing it to oscillate) and then brought into the vicinity of another 440 Hz tuning fork, the second tuning fork will begin to oscillate. The first tuning fork is said to have entrained the second or caused it to resonate. The physics of entrainment apply to bio-systems as well. Of interest here are the electromagnetic brain waves. The electrochemical activity of the brain results in the production of electromagnetic wave forms which can be objectively measured with sensitive equipment. Brain waves change frequencies based on neural activity within the brain. Because neural activity is electrochemical, brain function can be modified through the introduction of specific chemicals (drugs), by altering the brain's electromagnetic environment through induction, or through resonant entrainment techniques.
Brain waves are electrical activity patterns caused by the neurons of the brain communicating with each other. Brain waves can be detected using sensitive medical equipment such as an electroencephalogram (EEG) monitor. Brain waves provide an indication of the mental state of an individual. In other words, the appearance of brain waves is directly connected to what a person is doing, thinking or feeling. The different Brain states are: Gamma, Beta, Alpha, Theta, Delta. You have your own unique brain wave patterns that function habitually. Some of these brain wave habits are useful, and others need some fine-tuning. When your brain is functioning efficiently, your brain waves are “in sync” with your activity, but stress or lack of sleep can interfere with this natural harmonious relationship. To restore this harmony, at Gaia Meditation, we have developed a wide range of free audio programs, including meditation music, relaxation music, sleep music and plenty other Sound Healing programs.

The various mental states of the individual are thought to take place across a varied range of frequencies, or brainwaves. By encouraging the frequency following process, entrainment is able to create positive change in the brain, through matching carefully-selected frequencies of light and/or sound. The stimulus enables the individual to access a different state of consciousness, which can be useful for a number of benefits including relaxation, anxiety management, stress reduction and more.

I have purchased the two meditations I mentioned which are theta and 7 chakra frequencies. I tend to be a bit hesitant to register and/or buy from sites I don’t know, that’s why I asked you. But I got over my trust issues and already wrote the creator. He is most helpful. In case someone is wondering: the ‘higher spiritual awareness’ refers to a deeply meditative experience.
Some people believe that using this stuff can be a replacement for meditation. While sitting passively and listening to something that can give you the same effect frequency-wise as meditation, there is still far more benefit to meditating than just entrainment. Meditation and mindfulness allow you to really understand yourself on a level far deeper than technology will bring you.
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]