Passively listening to binaural beats may not spontaneously propel you into an altered state of consciousness. One's subjective experience in response to binaural-beat stimulation may also be influenced by a number of mediating factors. For example, the willingness and ability of the listener to relax and focus attention may contribute to binaural-beat effectiveness in inducing state changes. "Ultradian rhythms in the nervous system are characterized by periodic changes in arousal and states of consciousness (Rossi, 1986).
Isochronic tones are basically just a single tone with the volume being turned on and off at regular intervals. When you apply the same effects to music or a noise, it’s usually referred to as amplitude entrainment effects (in Mind Workstation anyway). When you apply the on/off effect to music or noise it’s usually done by targeting a specific frequency range in the sound and only turning that part on/off, leaving the rest of the music/noise untouched. What that does is allow parts of the music/noise to play without being distorted/interrupted, making it sound more pleasant to listen to. It produces a kind of fluttering sound as I like to call it and you can adjust the level of intensity.

Besides scientific literature, some authors have written of the promising research on meditation in books targeted for general audiences. One such book, Buddha’s Brain by Rick Hanson, PhD shares the current scientific research and investigations into meditation.[19] Hanson, a neuroscientist and researcher, explains to readers the scientific studies in plain language and discuss the impact of the results. Hanson’s main argument is that positive emotions, like love can be strengthened through meditation in a neuroplastic manner, citing dozens of scientific studies to support this claim.[19] Hanson’s viewpoint is representative of a larger popular movement to study and embrace Eastern phenomena including meditation in the Western world.
So to summarize their claim, they're saying that entrainment means that a binaural beat will cause your brain's electroencephalogram to match the pattern of the phantom beat. Well, if it did, entrainment certainly doesn't apply and would not be part of the equation, so we can scratch that off the list. But it doesn't make the claimed observation wrong. We do know that certain electroencephalogram waveforms are often associated with certain kinds of activity. For example, physical activity or REM sleep often produces an electroencephalogram with a sine wave of between 4 and 8 Hz, which we term a theta pattern. Waking relaxation with eyes closed often produces a pattern from 8 to 12 Hz, which is called an alpha pattern. There are only a few characterized patterns, and pretty general descriptions of what kinds of activities go with them. The claim made by the binaural beat sellers depends on much more granular and specific matches. For example, the claim that a binaural beat with a frequency of X produces the same effect in your brain as Vicodin is wholly implausible. Such claims presume that we know the exact frequency of the electroencephalogram in each of these desired conditions, and the fact is that brain waves don't work that way. It is wholly and absolutely implausible to say that desired brain condition X will occur if we get your EEG to read exactly X Hz.

Transparent Corp's Research Area is arguably the most comprehensive resource for collated brainwave entrainment research.   Update: the main research area on Transparent Corp's website is currently being updated, so it is offline.  However, you can still access their peer-reviewed research paper as a PDF here: “A Comprehensive Review of the Psychological Effects of Brainwave Entrainment“.

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In the average person, the activity of one brain hemisphere is dominant over the other, called brain lateralization. This hemispheric imbalance leads us to experience the world in a black and white way, perceiving separation over connectedness. When brainwave entrainment is used to synchronize brainwave activity in both hemispheres simultaneously, a person can more easily integrate information from all parts of the brain and solve problems with greater intelligence and sensitivity.
Do note the pre-sets slightly below to the right. Remember: Delta is for deep sleep. Theta is associated with dreaminess. Alpha is a blank or relaxed state of mind and Beta is when you’re active. Try to clear your mind of any thoughts and expectations, and set the volume to an acceptable level. You can play around, but try to give a minute or two for your state of choice. At first glance, you’d think this sounds like an alien spaceship, if not a microwave or a washing machine. Whatever it sounds like to you, if you give it an open mind you will notice there is something weird about this after all. Hopefully, your chosen frequency will have guided you towards the intended effect!
Slightly higher-frequency entrainment can lead to hyper suggestive states of consciousness. Still higher-frequency EEG states are associated with alert and focused mental activity needed for the optimal performance of many tasks. Perceived reality changes depending on the state of consciousness of the perceiver (Tart, 1975). Some states of consciousness provide limited views of reality, while others provide an expanded awareness of reality. For the most part, states of consciousness change in response to the ever-changing internal environment and surrounding stimulation. For example, states of consciousness are subject to influences like drugs and circadian and ultradian rhythms (Rossi, 1986; Shannahoff-Khalsa, 1991; Webb & Dube, 1981). Specific states of consciousness can also be learned as adaptive behaviors to demanding circumstances (Green and Green, 1986).  
One problem with researching binaural beats is that listening to them does not guarantee brain entrainment. Although a determined listener should be able to focus on the beats enough to relax and let his or her brain match the binaural beat wavelength, sometimes, and for some people, it just won’t happen.  Also, some claims, such as astral travel, are not scientifically measurable at this time, and so are unverifiable in scientific studies. However, there are several studies that suggest that a meditative state is more easily attained when listening to binaural beats, suggesting that other such states may well be acheiveable too.
James Austin, a neurologist, began practicing Zen meditation during a visit to Japan. After years of practice, he found himself having to re-evaluate what his professional background had taught him. "It was decided for me by the experiences I had while meditating," said Austin, author of the book "Zen and the Brain" and now a philosophy scholar at the University of Idaho. "Some of them were quickenings, one was a major internal absorption ­ an intense hyper-awareness, empty endless space that was blacker than black and soundless and vacant of any sense of my physical bodily self. I felt deep bliss. I realized that nothing in my training or experience had prepared me to help me understand what was going on in my brain. It was a wake-up call for a neurologist."
“…humans have always been intrigued by the possibilities for influencing mental functioning that emerge from combining rhythmic sound and rhythmic light stimulation. Ancient rituals for entering trance states often involved both rhythmic sounds in the form of drum beats, clapping, or chanting and flickering lights produced by candles, torches, bonfires, or long lines of human bodies passing before the fire and chopping the light into mesmerizing rhythmic flashes. From Greek plays to Western opera, our most popular entertainment forms have made use of combinations of lights and sounds. Some composers, such as the visionary Scriabin, actually created music intended to be experienced in combination with rhythmic light displays.”
I have been using the Equisync CDs at least 24 minutes 5 days a week. It instantly relaxes me, helps get rid of headaches and even hiccups! I have a stressful job and it helps prevent anxiety; I have not had a chance to check my blood pressure but I feel calmer. I have used other products before but I like the Equisync CDs much better; it is deeper and more relaxing.

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.