This phenomenon is fully described in the pertaining section [Distorter ] . For now it will suffice to highlight that distortion comes about when a signal gets saturated thus generating a whole set of new high frequencies.
To have a short glimpse of a distorted sound we report here two sounds: a plain guitar line and the same line after distortion has been applied:
A frequency with a high amplitude can mask nearby frequencies that have lower amplitudes. This happens because frequencies that are close to each other are picked up by hair-cells that belong to the same critical band. This characteristic is widely exploited to create digital audio data compression algorithms such as MP3 and ATRAC (used in MiniDisc systems [The MiniDisc ] ).