It reduces or completely discards certain parts of the audio that it deduces that the human ear can't hear, either because they are in frequencies where the ear has limited sensitivity, or are masked by other (typically louder) sounds.
On smanjuje ili potpuno odbacuje određene dijelove zvuka koje ljudsko uho ne može čuti, bilo zbog toga što su u frekvencijama ograničene osjetljivosti, ili su maskirani od drugih obično glasnijih zvukova.