When a string of the harp is plucked it starts to vibrate and produces a sound that continues with a steady rate of decay until the string vibrations fade away. The duration of this decay depends on the length of the string. The shorter the string the shorter its decay time.
The following example shows the average decay duration of the strings of the harp, provided each string is plucked with the same muscle strength, indicating the initial dynamic of a fortissimo. Notes that are played more softly/with less strength will in turn have a shorter decay time.[Inglefeld/Neill 1985]
Average sound decay.