I appreciate your compliment on my article Henry. I’ve been using and reading up on isochronic tones and brainwave entrainment for many years, so it was just a case of trying to put a lot of what I’ve learnt into one article. I don’t have a great deal of knowledge or experience in using hypnosis and subliminals, so I’m afraid I wouldn’t be in a position to create something so extensive in reviewing them.
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“.
Controlled or pre/post studies of the effects of BWE using auditory or visual stimulation were eligible for inclusion, provided pulses of light or tone were delivered at frequencies hypothesised to have a beneficial effect or in line with a protocol addressing clinical outcomes. Studies were required to report clinical or psychological outcomes (measured using standard methods or as deemed appropriate by peer review) and to report statistical analysis. Studies of outcomes such as electroencephalogram (EEG) response or neurotransmitter levels were not eligible. Case studies were excluded.
Some research suggests that the benefits from brainwave entrainment can last a lot longer, and still be seen for some time after you've stopped using it. Study participants have still maintained improved test scores a few weeks after the stimulation had ceased. Research on the long-term benefits has so far been minimal though, so how long the effects last is still up for debate.
Generally speaking, the brain will usually entrain to the strongest stimulus which would be isochronic tones over binaural beats. So when you see people add binaural beats at a different frequency to the isochronic tones, that would not produce additional brainwave entrainment at another frequency. If they are both at the same frequency I haven’t seen any research to indicate whether that would be beneficial or not, but my belief is that it would weaken the potential for entrainment. When you look at the waveform of an isochronic tone there is a distinct empty space between each beat, making it very pronounced and effective. When you add binaural beats at the same frequency it looks like this: http://www.mindamend.com/wp-content/uploads/2017/11/isochronic-tones-binaural-beats-combined-waveform.jpg. The depth of the waveform is now half as deep and less effective. This is before the binaural beats are formed inside your head, where the waveform is hard to determine and measure. From listening to that type of combination the beats sound much less pronounced, which has to make them much less effective in terms of a brainwave entrainment stimulus, compared to isochronic tones on their own.
Biofeedback enhancement: In 1981, researcher Arturo Manns discovered that 15 minutes of stimulation with isochronic tones enhanced biofeedback protocols for bruxism (grinding of teeth). They did this by increasing muscle relaxation superior than standalone biofeedback. Brainwave entrainment is different from biofeedback in that it does not allow the person to consciously control their brainwave state.
Brainwave Mind Voyages 30 CD Set: Brainwave Meditation Programs, Hemispheric Synchronization, and Brainwave Entrainment Technology (30 BMV CDs: Lucid Dreaming, Astral Trance, Alpha Brainwaves, Theta Brainwaves, Delta Brainwaves, Tones, Astral Vibrations, Remote Viewing, Beta Brainwaves, Lucid Dream Cycle, Lucid Dreams Hypnosis, Guided Dream Incubation, The Whales CD, Rainstorm, The Waters CD, Nature Sounds, Heartbeat Meditation CD, The Om Meditation, Ganzfeld Effect/ White Noise, Breathing Silent Mindfulness, Breathwork Yoga, Tibetan Singing Bowls, Schumann Resonance, Sacred Healing Frequencies Solfeggio Healing Tones, Sacred Geometry, Celestial Sounds, Audio Mind Machine Sessions, Awakened Mind Brainwave Pattern, Float Tank Hypnosis Session, Full Body Mind Massage Hypnosis)
Basically, one frequency of sound plays through one speaker/headphone and a different sound frequency plays in the other speaker/headphone. With these two different frequencies playing in each ear separately, but at the same time, your brain automatically tries to make up the difference in this frequency range and therefore is gently brought into a new, desired brainwave state as described above. An example of this effect would be a 100Hz frequency playing in your left ear and a 105Hz frequency playing in your right ear. Your brain, over several minutes, distinguishes the slight difference in frequencies and automatically adjusts its brainwave state to match this difference – being 5Hz in this example and therefore putting your brainwave into a Theta state. Pretty cool huh?!
If brainwave entrainment leaves you with unwanted side-effects (see below) or discomfort, you’re probably encouraging a range of brainwaves that are already excessive in some area of your brain. The way around this is to get a brain map to see what your brain’s strengths and weaknesses are, and see what (if any) brainwaves could use some encouragement.