earmuffs vs headphone

earmuffs

noun
  • A headphone-like device designed to cover a person's ears for protection against cold or noise. They consist of a thermoplastic or metal head-band, that fits over the top of the head, and a pad at each end, to cover the external ears. 

headphone

noun
  • A cushioned speaker placed on, over, or inside the ear, normally used in left/right pairs. 

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