Audio compression is used to change the differences in level of a piece of music or other sound source. Dynamic range is the difference between the loudest and softest passages. The range of loudness and softness of music today can vary greatly. Much of pop music has a low. This means the difference between the loudest and softest parts is small. A good level of dynamics in a current piece of music might be 14db where as a very limited and compressed example could have just a few decibels of range.