When the volume of the recorded sound is changed, the degree of change is usually expressed in terms of decibels or short dB. This is a common unit in connection with audio. In Mp3 Audio Editor, decibel is used to express the extent of change relative to the original level.
Special for the decibel unit is that it is based on a logarithmic scale. Zero dB represents no change, whereas an increase of six dB represents a doubling of the signal amplitude. Reducing by six dB results in half the signal amplitude.
The decibel dB versus intensity change in percent
The decibel scale is chosen to suit the sensitivity curve of the human ear which have the same logarithmic property.