aftersound

noun3

1. •
   A sound that persists or remains audible after its source has ceased to produce it; the perception of such a sound.

   • […] the strings of an instrument, […] being strucken with the hand, do verberate the ayre in its first sound, and are reverberated by the ayre to an after-sound. — 1659
2. •
   The second, slower phase of decay in the sound made by a piano string when it is struck.
3. •
   (no longer used) A weaker sound that immediately follows a more salient one, such as the second, less prominent vowel sound in a falling diphthong.

   • In English I cannot hear the sound of Italian o chiuso, but only that of (o 5) followed by an aftersound, as in home, or without this aftersound, as in more. — 1881