voiced vs vowel

voiced

adj
  • That contains voice. 

  • Sounded with vibration of the vocal cords. For example, the phone [z] is voiced, while [s] is unvoiced. 

  • Having a specified kind of voice. 

vowel

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

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. 

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