mumble vs talk through one's hat

mumble

verb
  • To speak unintelligibly or inaudibly; to fail to articulate. 

  • To chew something gently with closed lips. 

noun
  • A quiet or unintelligible vocalization; a low tone of voice. 

talk through one's hat

verb
  • To speak lacking expertise, authority, or knowledge; to invent or fabricate facts. 

  • To assert something as true or valid; to bluff. 

How often have the words mumble and talk through one's hat occurred in a corpus of books? (source: Google Ngram Viewer )