brush off vs turn down

brush off

verb
  • To disregard (something), to dismiss or ignore (someone), as unimportant. 

  • Used other than figuratively or idiomatically: see brush, off. To remove something with a brush. 

turn down

verb
  • To refuse, decline, or deny. 

  • To reduce the power, etc. of something by means of a control, such as the volume, heat, or light. 

  • To reposition by turning, flipping, etc. in a downward direction; to double or fold down. 

How often have the words brush off and turn down occurred in a corpus of books? (source: Google Ngram Viewer )