earmuffs vs earphones

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. 

earphones

noun
  • A pair of small loudspeakers worn inside each outer ear or covering all or part of the ear, without a connecting band worn over head. 

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