I have spending time in a floatation tank for the last 9months and just recently added the audio of crystal bowls into the tank. HOLY FLOAT! If you have experienced the bowls live then you know the physical experience that they produce; aside from the meditative side. Well, this effect is accentuated 10fold while in the tank. I have also started to float with binural entrainment audio and have seen a few effects.
Theta waves also have been observed in moments when a person recalls information from the past, and this may be what links them also to improvement in learning ability. We also experience theta waves when we go into automatic pilot mode, such as when doing a repetitive task like driving a familiar route where the mind become disconnected while you still drive safely toward your destination.
To summarize all this, we can see that the type of product you choose plays an important role in answering that question – “Can brainwave entrainment damage my brain?” My personal advice as a long-term user of the technology is to Be selective about what brainwave entrainment audios you download from the internet, and make sure to follow the instructions! 
From a brainwave entrainment effectiveness perspective, it’s my understanding that the response from isochronic tones stimulation starts to diminish over 30Hz and that 40Hz is about the limit for using them. So from what I’ve read on the topic a 100Hz beat wouldn’t work, probably because it’s too fast for the brain to process and synchronise with it.
I just wanted to thank you guys for having such an outstanding product available. I used to meditate when I was younger but got away from it over the last 7-8 years. I had difficulty starting back up, but since I started using your cds I have no difficulties getting back into it; and am now meditating 2 hours per day and have never felt better. I have only been using them for a couple weeks but have already noticed a difference. Thanks again for creating such a wonderful product and I will be sure to recommend it to everyone.
This thing blows my mind! The first time I used it I was like "No way!" As I kept using it I discovered that it is literally the only way I am able to fall asleep nights when my mind is so full of thoughts and my anxiety is running rampant! I hate the way sleep aids make me feel like I've been run over by a freight train. I recently switched from using "Deep Sleep" to "Dreamy Sleep" and had the craziest dreams! I normally can't remember my dreams and I was actually able to recall quite a bit of them. Unfortunately last night, I dreamt that I faked the death of my dog last year and I felt like it lasted the whole night so I think I'll be switching back to "Deep Sleep" :( Awesome product though. My *only* complaint is that I wish there were more ambiance options or the ability to use it with Pandora. You can use your own music but I don't have much personal music on my phone so I am limited to using the app's ambiance tracks and they get old after a while. Highly recommend!
Brainwave entrainment is a colloquialism for such 'neural entrainment', which is a term used to denote the way in which the aggregate frequency of oscillations produced by the synchronous electrical activity in ensembles of cortical neurons can adjust to synchronize with the periodic vibration of an external stimuli, such as a sustained acoustic frequency perceived as pitch, a regularly repeating pattern of intermittent sounds, perceived as rhythm, or of a regularly rhythmically intermittent flashing light.
It has been both a pleasure and an enlightening experience listening to the Equisync II CDs for the past month. As a 15 year stroke survivor, daily meditation has become a part of my life. Listening to these CDs reminds me of sitting alone in a forest during periods of rain, whether they be light, heavy, or in between. I am able to access my right hemisphere more readily and experience the feeling of nirvana that we all have within us. When I reach this point, my system reminds itself of all the compassion and connectedness we each have.
I forgot to tell you, after using your meditation for a few weeks, I woke up one morning with the most vivid recollection of having an out of body experience […shortened…] I am hoping to experience this again and control myself the next time. Thank you for enabling me to remember this extraordinary experience. I never believed they were real until I used your program.
Audio-visual entrainment (AVE) is an effective tool for dissociating the depressed/anxious person out of his/her destructive thoughts. Even with increasing anxiety, AVE has been shown to reduce heart rate … reduce jaw tension from stress … increase blood flow in the eyes … and increase peak-alpha frequency … Many homes have two to three [AVE] systems in them for family members to use following a stressful, tiring day in the modern world.

Again, it is important to be cautious of claims for things like these, and to find a brainwave entrainment seller that you can trust to make quality audios. It is incredibly easy for someone to throw together an audio without much to it and make all kinds of claims about what it can do for you. Please feel free to read through our reviews on the site to see some of the products I have tested and found to be of a reputable quality.

There isn’t really a one-size-fits-all track or frequency range which is right for all kids while doing homework. So that does make it difficult to recommend one thing in particular, and why I have a number of tracks for studying and focus. If they have already learnt and understood the information, but are just trying to commit it to memory for a test, then I would recommend an alpha track, like the Memorization Study Aid product I have with the 10.4Hz frequency you referred to. If they are still trying to fully understand what is being taught in a workbook, then I would recommend a track that is mainly beta frequencies, like my Study Focus tracks. In the middle, I have a number of tracks which use a combination of beta and alpha wave frequencies, like Study Booster, Study Enhancer and Cognition Enhancer. The last 3 use similar frequencies but deliver the tones and brainwave entrainment effects in different ways. As we are all wired a little differently it does sometimes take a bit of trial and error, to see what method or frequency range works best for the individual. These types of tracks are made for a general audience. In an ideal world, you would hook up to an EEG and see in real time exactly what a person responds to best, depending on the goal and current state of mind.

I personally have been experimenting with binaural beats – both in and out of the float tank – for the past year or so and they have quickly and easily become one of my favourite go-to “hacks” for helping me achieve a desired state of being. From listening to a specific track right before going to sleep which helps put my mind and body in a state of relaxation and recovery to, on the flip-side, listening to a track that helps prime my brain-state for creativity and focus right before I sit down to do some work – like writing this blog! They are also an enjoyable and effective asset to try out and experiment with while in the float tank. For the reasons mentioned above, as well as the sound frequencies can resonate a subtle but noticeable vibration in the tank, water and your body making for quite the unique floating experience!
The formal name for this process is called the “frequency following response”, where the human brain will literally “follow” a specific frequency/beat after being exposed to it for (usually) about 8 minutes.  Technically the definitive term “entrainment” does not exactly match the actual process of what is happening to your brain when listening to these audios, but its close enough, and the name has stuck now with these products becoming more popular and widely known.

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’m sorry to hear you’re having these troubles. First off, I disagree with whoever told you it was a good idea to listen to 6 subliminals a day. I suppose I would need more context to better understand. Are these binaural beats or brainwave entrainment audios? If so you are definitely listening too much, and can harm yourself (just as the article mentions above from over-doing it). Even if they are not brainwave entrainment audios, I cannot imagine it is effective or the best idea to listen to so much so often. I would pick one subject that correlates to the most important goal for you and stick with it until you have achieved it. Remember to steer clear of that tempting idea of getting “all that you want for nothing”. Even subliminals are a tool. You still have to use the tool to do the work.

There are many sources of binaural beats on the internet and YouTube to check-out and experiment with yourself – I recommend using headphones for optimal effectiveness. However, like most things, not all binaural beats are created equally (especially if they are free on the internet) and therefore not as effective or enjoyable to listen to. This is why I HIGHLY recommend the binaural beats created by master audio technician, music producer and meditation teacher, Cory Allen – which can be found here:

A crossover RCT of a single session of theta stimulation in four healthy adults reported no significant improvement in verbal fluency or attention associated with the intervention and a reduction in immediate recall. Controlled comparisons reported significant benefit from the intervention in all three outcomes measured. Six pre/post studies reported significant benefit from the intervention for 19 of 28 cognitive outcomes.