ear bud vs headphone

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. 

headphone

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

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