Definition of "devocalize"

devocalize

verb
third-person singular simple present devocalizes, present participle devocalizing, simple past and past participle devocalized
1. (transitive, phonetics) To make toneless; to deprive of vowel quality.
  Quotations
  If we take a high vowel […] and devocalise it, we obtain a hiss […]
  1877, Henry Sweet, A Handbook of Phonetics
2. (transitive) To reduce the volume of the vocalizations of (an animal) by surgically removing tissue from its vocal cords.