inarticulation vs voice production

inarticulation

noun
  • The state of being inarticulate; inarticulateness. 

  • An inarticulate or underarticulated utterance. 

  • Any point in the educational system in which the development of the individual is hindered. 

voice production

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