Micro electros are able to detect a sort of very small scale electrical activity in specific parts of the brain. So he's getting real activity of his own brain cells in the form of sound that he can then modulate activity by changing his thoughts. By being provided his constant feedback of what is going on in his brain, he then asks, what? Can you push it up or can you push it down? Can you dile it up? Can you dial it down?Can you dial up or down the sound? Yes, exactly.