Alright, I got some fuel for your fire that you'll find to be very interesting.
The brainwaves that you guys are talking about are Theta waves, which are defined as being between 3 1/2 and 7 1/2 hz. Alpha waves are a bit higher in frequency - 8 to 12 hz.
Jumping around a bit now.
In REM sleep (dream sleep) the brain is very active, often times producing bouts of beta wave, which have an even higher frequency than alpha (beta waves appear when the brain is at work in waking state). But also within REM sleep Theta waves appear, originating from the Hippocampus - the structure in the brain thought to mediate long term memory.
It is widely thought (with supporting evidence of course) that the main purposes of REM sleep is learning. During REM the brain integrates info learned throughout the day with older stores of info. There's a good chance that this is why many elements from your past occur in dreams of present situations.
Within the hippocampus, if a neuron is fired in rapid succession the syapses that are excited become "strengthened", meaning that they can more readily cause the receiving neuron to fire. This is thought to mediate memory (also see Memory thread in Human Sciences forum), the more times the neuron is stimulated the more it is strengthened. However, the syapses will only be strenthened if it is excited after a certain interval after the receiving neuron just fired. This interval is the same as a Theta wave.
So the theory is Theta waves are produced by the hippocampus to mediate the strengthening of synapses, which make those neurons more readily fireable. Certain neurons (or clusters of) are assigned to certain memories and their "info" is recalled better (due to strengthening of associated neurons) if they are stimulated one theta wave after there last action potential(s). And long-term memory is needed for learning (this is pretty obvious).
So maybe these low frequencies you are talking about radiate into the brain and facilitate the integration of new info (learning) while one is awake. Basically doing what the hippocampus does while in REM sleep - radiate Theta waves, providing a timer for synapse strengthening - learning. You could maybe make a leap and say that these waves are inducing an pseudo-REM-like state in waking life.
First of all, the brain considers any sensory input as data to be translated and the meaning is used. A pure sine wave or square wave does not have any meaning (no real data). So the neuron firing threshold will increase to filter out the stupid noise.
It's true that the brain filters out stimuli that are meaningless but Theta waves are very low frequency waves and can travel right through your skull - they don't need to be picked up by the ears. As stated above, they could possibly affect the brain at a neuron to neuron level. What you are talking about is at a data/information level.
First of all he said low frequency sound in the range you described can make you sick.
I've heard this too and it's probably true. I wonder what range exactly is the "sickness range". Theta waves are very specific (3 1/2 to 7 1/2). Also, the body likes balance, homeostasis. For the body, there's always too much of a good thing. So I'm guessing that too much of these Theta waves may not be productive. There must be a "reason" why Theta waves only occur at certain times, such as sleep.
I would say being exposed to Theta waves while meditating would be a good thing. I would say that some person who straps a Theta generator to his/her head to try and "learn more" may be going to far and causing more damage than anything.
If any of this needs clarification please ask away. I'm moving things the next few days though, so I may not be able to get back to you right away.
hope this helps,
-Xenu
Thank you Joeman.