 Part 3 of the MPEG-1 standard covers audio and is defined in ISO/IEC-11172-3.MPEG-1 Audio utilizes psychoacoustics to significantly reduce the data rate required by an audio stream.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.