I know I have a rather acute sense of hearing - I hear my TV "hiss" in standbye, I could always perceive my PDA "humming" when reading in bed... I hear a lot of sounds other people don't hear.
But until now I hadn't realized the Kobo was making a sound when turning the pages, which it actually does. The sound is very soft, though, so it has to be really quiet in order to hear it - or I have to press my ear to the back of the Kobo.
Kind of reminds me of the sound of a page turning mixed with white noise. Very appropriate for an eReader in my ears.
