hum vs murmur

hum

noun
  • An often indistinct sound resembling human humming. 

  • Unpleasant odour. 

  • A phenomenon, or collection of phenomena, involving widespread reports of a persistent and invasive low-frequency humming, rumbling, or droning noise not audible to all people. 

  • Busy activity, like the buzz of a beehive. 

  • A hummed tune, i.e. created orally with lips closed. 

intj
  • Synonym of um: a noise indicating doubt, uncertainty, &c. 

  • Synonym of hmm: a noise indicating thought, consideration, &c. 

verb
  • To produce low sounds which blend continuously 

  • To express by humming. 

  • To reek, smell bad. 

  • To make a sound from the vocal chords without pronouncing any real words, with one's lips closed. 

  • To drone like certain insects naturally do in motion, or sounding similarly 

  • To buzz, be busily active like a beehive 

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 hum and murmur occurred in a corpus of books? (source: Google Ngram Viewer )