Many people said my English is awful, but whatsoever...I have question to ask.

What is exactly brainwave? How is it measured? I just read an article about a brainwave machine which it said can tune one's brainwave to certain frequency at which it said that one's brain is perfect for doing certain things, such as learning with the frequency of one's brainwave between 14Hz - 30Hz. My questions here are:

1. Can one's brainwave be tuned by feeding one ear with a steady tone of 500Hz and the other ear a steady tone of 510Hz? It said this way 10Hz is perceived by the brain and is a very effective stimulus for brainwave entrainment. Sounds ridiculous to me.

2. If it's true that the frequency of one's brainwave is between 14Hz - 30Hz when one is highly alert and focused, then vice versa? I mean is the frequency of brainwave the only indicator for brain state? How about the intensity of brainwave? How about other factors such as chemical environment of the brain?

There're many learning enhancing or brain manipulating products on the market, I'm just very skeptical about their factual effects. What are you thinking about this kind of products?

apologize for my bad grammar. []