aphonic vs voiceless

aphonic

adj
  • Of, relating to, or exhibiting aphonia; unable to speak. 

noun
  • A person who has aphonia. 

voiceless

adj
  • Lacking a voice, without vocal sound. 

  • Spoken without vibration of the vocal cords; unvoiced, surd, breathed. Examples: [t], [s], [f], [m̥], [u̥]. 

  • Without a vote; having no input into a decision. 

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