mouthing vs vocalization

mouthing

noun
  • Ranting; passionate speech devoid of meaning. 

  • The act of forming a shape with the mouth, especially as part of sign language. 

vocalization

noun
  • The act of vocalizing or something vocalized; a vocal utterance 

  • The production of musical sounds using the voice, especially as an exercise 

  • The change in pronunciation of historically or variably consonant (typically sonorant) sounds as vowels. For example, the syllabic /l/ in words like people or the coda one in words like cold or coal are variably realized as a high back vowel or glide—[ʊ], [u], [ɤ] or [o]—in many dialects of English in the US, UK, and the Southern Hemisphere. For example, in African American Vernacular English, one common pronunciation of the words "people", "cold", and "coal" is [pʰipʊ], [kʰoɤd], or [kʰoɤ] respectively. 

  • The addition of these diacritics and the respective phonemes to a word; the spoken form the word thereby receives. 

  • Any specific mode of utterance; pronunciation 

  • The use of speech to express an idea 

  • The vowel diacritics in certain scripts, like Hebrew and Arabic, which are not normally written, but which are used in dictionaries, children's books, religious texts and textbooks for learners. 

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