Neurological damage from listening to two tones of differing pitch in the right and left ear?
Riiiight.
It's tones. That's all it is. Tones with a bunch of marketing behind it.
I think the role of intention and expectation is at least half of the equation. This isn't based on verifiable statistics or scientific fact, but that's ok, because none of the claims made by the people who create these products are either.
I believe there may be studies on the effects of meditation on short term and long term memory. I think, if I recall correctly, short term memory of meditators is reduced while long term memory increases. Again, I may be mistaken about this.... but I do recall a study being done and those being the results.
There is too much pseudo-science and BS involved in this brainwave activity and entrainment hubbub. People involved in studying brainwave activity will tell you that generalizing a person's collective brainwave activity into an "alpha" brainwave or "delta" is complete nonsense. These labels and cycles per second are just vast generalizations used to try and get a handle on what is going on in the brain, which is a literal cacophany (or symphony) of simultaneous activity of varying levels and degrees.
No one at any time has an "alpha" brainwave. A person has brain activity, some of which in a part or parts of the brain that may be described as alpha for a given period of time. Simultaneously there are "delta" waves, "beta" waves, etc.
Also, you may be surprised to know that a "delta" tape does not necessarily produce an abundance of delta waves in the brain. Also, the qualities associated with different types of brainwaves as well as so-called brain synchrony may not actually be produced when the brainwaves are present.
Think of how complex the brain is. Think of how complex an activity like creativity is. Do you reall think that a tape that *supposedly* puts you into a theta brain wave will make *your brain* (which has significant differences in makeup and function from other brains) go into what *you* consider to be a creative state?
What happens when what part of the brain is generating a majority of a certain "type" of brainwave? Do you really think these companies have mapped that out and have technology sufficiently advanced to create that specific a kind of change in brainwave activity through the use of sounds? Even worse, think of the clumsiness of the tool being used ... binaural beats. A tone of one pitch in one ear, and another pitch in another ear.
Comon.
I do admit that these tapes have effects on people. They tend to be relaxing. Then again, Bach is relaxing, too, and far more complex.