How do MP3s provide clear sound at such a small file size?
MP3 (or Moving Picture Expert’s Group audio layer-3) is a compression method and file format for digital music that allows for near-CD quality sound, but at a fraction of the file size. A WAV-format track of 3 minutes in length can easily run to around 30MB in size; an equivalent MP3 is around 3MB. This makes it especially suited to tranmission over the internet, and easy storage. It employs an algorithmic method during encoding called ‘Perceptual Noise Shaping’, which eliminates parts of the tracks that we cannot hear. These include: • Extremely high or low sound frequencies (20Hz to 20,000Hz) • Sounds that are not heard as well as others by the human ear • Multiple sounds being played simultaneously, where one is louder than all the others – the loudest noise is kept, and other elements are removed. By omitting these sections of the track when it is being encoded into the MP3 format, we are able to drastically reduce the file size, without any noticeable loss in sound quality.
