hum vs whisper

hum

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 

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

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

noun
  • 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. 

  • An often indistinct sound resembling human humming. 

whisper

verb
  • To make a low, sibilant sound. 

  • To speak softly, or under the breath, so as to be heard only by one near at hand; to utter words without sonant breath; to talk without that vibration in the larynx which gives sonorous, or vocal, sound. 

  • To speak with suspicion or timorous caution; to converse in whispers, as in secret plotting. 

  • To mention privately and confidentially, or in a whisper. 

noun
  • A private message to an individual in a chat room. 

  • A low rustling sound, like that of the wind in leaves. 

  • A rumor. 

  • A faint trace or hint (of something). 

  • The act of speaking in a quiet voice, especially, without vibration of the vocal cords. 

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