ear bud vs earphones

ear bud

noun
  • A small earphone designed to be placed in the ear canal for use with portable sound systems. 

  • An immature ear of maize from which the threadlike silks emerge. 

  • An underdeveloped mammalian ear. 

  • A cotton swab. 

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 ear bud and earphones occurred in a corpus of books? (source: Google Ngram Viewer )