Ah, yes. But remember, individual results will vary. I live near the Monterey aquarium, and there was a display that displayed a sound at (I believe) 15hz. It stated that this was below the threshold of NORMAL human hearing, but SOME humans could actually hear it. I was with a friend, and I told her to close her eyes, and I pressed the button on the display, and she told me when the sound came on and went off. I knew only because of the little light on the display. But she knew with her eyes closed and could hear it. (could have been 16hz, but around there)