aftersound vs murmur

aftersound

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

  • The second, slower phase of decay in the sound made by a piano string when it is struck. 

murmur

noun
  • Any low, indistinct sound, like that of running water. 

  • The sound made by any condition which produces noisy, or turbulent, flow of blood through the heart. 

  • A muttered complaint or protest; the expression of dissatisfaction in a low muttering voice; any expression of complaint or discontent. 

  • Soft indistinct speech. 

verb
  • To say (something) indistinctly, to mutter. 

  • To speak or make low, indistinguishable noise; to mumble, mutter. 

How often have the words aftersound and murmur occurred in a corpus of books? (source: Google Ngram Viewer )