phonation vs stammer

phonation

noun
  • The process of producing vocal sound by the vibration of the vocal folds that is in turn modified by the resonance of the vocal tract. 

stammer

noun
  • The involuntary repetition of a sound in speech. 

  • A speech defect whereby someone speaks with a stammer 

verb
  • To utter with a stammer, or with timid hesitancy. 

  • To keep repeating a particular sound involuntarily during speech. 

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