even though the human ear can’t consciously perceive sound above 20KHz — (15–16KHz in most cases), brain activity is still affected by the presence of bandwidth extended as far as 32KHz or more. It could have to do with phase relationships between audible frequencies, which become more exact at higher resolutions, or the mere fact that the natural world imposes no 20KHz limit on frequencies transmitted through the air — (indeed there are ultrasonic frequencies present all around us) — and that we’re aware of them without “hearing” them, but in tests where the same material was presented with and without extended frequency response, listeners, without being aware which one was being listened to, preferred the extended frequency-response versions of the recordings well above statistical random.