hearing vs tone color

hearing

noun
  • The sense used to perceive sound. 

  • A proceeding at which discussions are heard. 

  • The act by which something is heard. 

  • A legal procedure done before a judge, without a jury, as with an evidentiary hearing. 

adj
  • Able to hear, as opposed to deaf. 

tone color

noun
  • Synonym of timbre (“quality of a sound independent of its pitch and volume”) 

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