The above site is a physical explanation of what binaural beats (which are the same as tones) are, and how the hallucination occurs. The hallucination is auditory, and its the beat you hear when you listen to the tones, and it is caused by the brain trying to figure out where the sound is coming from. It is not visual.
Furthermore, the blog concludes that the marketed auditory tones are false in their claims, and do not do anything. It does, however, cite a study that shows evidence of the tone's ability to alter brain states.
Here are the problems. The blog does not cite any evidence (and specifically states there is no evidence) of brainwaves changing due to the sounds. It is all "theory" as it states. I looked into the study cited in the article, and here it is:
What IS the Monroe Institute? Well I looked that up as well.
"The Monroe Institute® is a nonprofit 501(c)(3) educational and research organization dedicated to the exploration of human consciousness, and is internationally known for its work with audio sound patterns that can have dramatic effects on states of consciousness. This patented audio-guidance technology is known as Hemi-Sync®."
Its a nonprofit organization invested in a copyrighted audio-guidance technology? WHAT? That doesn't sound so even-handed to me. Here's more:
"The Monroe Institute is devoted to the premise that focused consciousness contains definitive solutions to the major issues of human experience."
Yep, they're out to prove a point. Not only that, but if you look in their book store, they sell books about psychic powers and hypnotic sleeping aids (which have been shown by REAL researchers to not work at all.)
So then whats really going on? Well, besides money-mongering and scams, there actually IS something to binaural beats. I looked at a few REAL studies with REAL data, and here's what I found:
These three separate studies are published on a government website by actual doctors under the support of the National Institutes of Health and the U.S. National Library of Medicine.
They show potential benefits in binaural tones for relaxation in people with mild anxiety. Most interestingly, they were compared to music in relaxing patients who suffer from pre-operative anxiety before surgery. There is NO study, however, to suggest that binaural beats cause visual hallucinations, nor that they directly affect brainwaves.
So in conclusion, it seems there is evidence to suggest that Binaural Beats can relax individuals who suffer from mild anxiety. However, there is no evidence or study to show that they have any direct effect on consciousness, nor do they provide experiences at all on the levels of hallucinogenic drug use. Binaural Beats are just interesting phenomena, not magical brainwave manipulators.