phonation vs vowel

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. 

vowel

noun
  • A sound produced by the vocal cords with relatively little restriction of the oral cavity, forming the prominent sound of a syllable. 

  • A letter representing the sound of vowel; in English, the vowels are a, e, i, o, u, and y. 

verb
  • To add vowel points to a consonantal script (e.g. niqqud in Hebrew or harakat in Arabic). 

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