Whenever we become very relaxed and the usual chatter of the mind slows down a little bit, if we remain aware and do not slip into sleep or unconsciousness, we begin to perceive things that we had not noticed before. This is slightly different than the issue of “expectations” discussed previously, although a relationship to them can develop which will be discussed below. These have to do with the fact that in our typical state of consciousness our mind is racing so fast and so loud, and our body is so engaged with activity and physical tension, that we are unaware of some subtle perceptions that are there all the while, but which get buried beneath all the physical and mental noise.
Binaural beats are an auditory illusion where two oscillators, slightly detuned from each other, are played simultaneously with one perceived by each ear. The human brain mixes the audio from each ear, and the listener perceives a "beating" effect that isn't actually there. This is a well-studied phenomenon that has gained the interest of audiologists and neurologists, but it's most famous for being picked up by the alternative medicine community as a way to get high.
Delta (3hz – 0.2hz) – Deep, dreamless sleep. Intuition. Empathy. Brainwave expert Judith Pennington calls it the doorway to Universal Consciousness and “A radar that scans the environment and psychically picks up information and energy.” According to British physicist C. Maxwell Cade “There have been reports that delta waves appear at the onset of paranormal phenomena.” (More information can be found in Cade’s book The Awakened Mind)
When explaining this to others they frequently respond with something like, “But I had no expectation or even any idea that my face might experience flushing. I didn’t even know that was possible. Now every time I listen to a particular entrainment track that specific face flushing occurs. If it is a specific phenomena, and it only happens when I use one certain entrainment track, doesn’t that prove it is the entrainment causing it?”
Alpha: Alpha brainwave patterns are associated with a state of wakeful relaxation. Slower and lower in frequency (between 9-14 hertz), alpha waves are dominant when we’re calm and relaxed, but still alert. Alpha waves are associated with states of meditation (your yoga class probably puts you in an alpha state), and also with our ability to be creative.
It cannot be any wonder then that we are almost desperate to find some sign, some indication that meditation and brainwave entrainment is having tangible, definable effects. We seize on these odd little experiences like ‘flushing of the face’ or ‘seeing spirals of color’ when our eyes are closed, hoping these are signs suggesting the elusive relief we’ve been after is finally within our grasp. We ask others to validate our experiences so that we can reassure ourselves we’re on the right track at last.
For our ancestors, stress was a survival skill during brief, life threatening situations. Once the danger passed, their stress levels lowered. However, in today’s world, we are constantly bombarded by stressors, such as work deadlines, traffic, and family obligations. We rarely get a break long enough to relax and relieve the stress. The over-activation of our stress hormones have been linked to high blood pressure, heart attacks, lower immunity, depression, anxiety, and more.
The composer Alvin Lucier has written many pieces that feature interference beats as their main focus. Italian composer Giacinto Scelsi, whose style is grounded on microtonal oscillations of unisons, extensively explored the textural effects of interference beats, particularly in his late works such as the violin solos Xnoybis (1964) and L'âme ailée / L'âme ouverte (1973), which feature them prominently (note that Scelsi treated and notated each string of the instrument as a separate part, so that his violin solos are effectively quartets of one-strings, where different strings of the violin may be simultaneously playing the same note with microtonal shifts, so that the interference patterns are generated). Composer Phill Niblock's music is entirely based on beating caused by microtonal differences.
Many of our common symptom-soothing formulas are designed to take effect within 5-10 minutes if used properly. To get these fast-acting results, we recommend 3-4 droppers full, or 6-8 pumps, per use to start. If you are not yet feeling the full effect within the first 5 minutes, repeat the original serving. You can do this up to 4 servings back to back. Note that some of our formulas are tonics and are meant to work over longer periods of time.
To use your senses to quickly relieve stress, you first need to identify the sensory experiences that work best for you. This can require some experimentation. As you employ different senses, note how quickly your stress levels drop. And be as precise as possible. What is the specific kind of sound or type of movement that affects you the most? For example, if you’re a music lover, listen to many different artists and types of music until you find the song that instantly lifts and relaxes you.
Delta brainwaves are slow, loud brainwaves (low frequency and deeply penetrating, like a drum beat). They are generated in deepest meditation and dreamless sleep. Delta waves suspend external awareness and are the source of empathy. Healing and regeneration are stimulated in this state, and that is why deep restorative sleep is so essential to the healing process.
Other than that the experience of those brainwave states is no different. Once we achieve a particular brainwave state using entrainment there is one significant difference to the experience and that is that we are usually still at a high level of consciousness. We’re not (hopefully) zoned out as we are when daydreaming or unconscious as we are when we’re sleeping. We maintain awareness and therefore we get to consciously experience what those brainwave states feel like in some detail.

Your brainwave activity during sleep is largely distinct from your brain activity when you’re awake. (REM sleep is one exception to this—during REM, your brain is active in ways very much like when you’re awake.) During non-REM sleep, the slower, lower frequency theta and delta waves dominate, compared to the alpha and beta waves that are prominent when you’re alert and active.
Theta brainwaves in the frequency range of 6 to 9 hertz are known as thalpha waves because of their proximity to alpha waves. They are seen during states of high suggestibility, during hypnosis, and during paranormal experience and are also connected to an increase in human growth hormone (HGH) levels and higher blood flow to the brain. Theta brainwaves sit between the realms of the subconscious and conscious mind, making them an especially useful brainwave state for developing creative thinking, working through emotional problems, and integrating subconscious and conscious experience. 
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.
There is no single relaxation technique that is best for everyone. The right relaxation technique is the one that resonates with you, fits your lifestyle, and is able to focus your mind and interrupt your everyday thoughts to elicit the relaxation response. You may even find that alternating or combining different techniques provides the best results. How you react to stress may also influence the relaxation technique that works best for you:

... Audio visual stimulation effects people on two levels: Budzynski (2001) reports significant improvement of mental capabilities after AVS in 75-year old male. Cruceanu and Rotarescu (2013) proved that the exposure to 30-minutes of audio-visual stimulation with the frequency of 10,2 Hz significantly improves cognitive skills. Based on their research, authors claim that people need to be exposed to AVS at least for 20 minutes in order to achieve positive effects. ...

Research: the authors stated that qualitative electroencephalogram signatures needed to be developed for different disorders and tested using standard validated methods of psychological assessment. Larger RCTs were needed with clear inclusion criteria for participants. The RCTs should measure qualitative EEG, hormone levels and the time of day of the intervention. Interventions protocols should be clearly defined and the relationship between session frequency/ duration and outcomes should be explored. More studies of auditory stimulation were needed, as well as studies comparing different types of stimulation, monaural, binaural and isochronic beats and use of white noise versus music.
The activity of neurons generate electric currents; and the synchronous action of neural ensembles in the cerebral cortex, comprising large numbers of neurons, produce macroscopic oscillations. These phenomena can be monitored and graphically documented by an electroencephalogram (EEG). The electroencephalographic representations of those oscillations are typically denoted by the term 'brainwaves' in common parlance.[4][5]