The Collaborative International Dictionary of English v.0.48:

deaf-aid \deaf-aid\ n.
   an electronic device which amplifies sound and is worn to
   compensate for poor hearing.

   Syn: hearing aid.
        [WordNet 1.5] deaf and dumb

WordNet (r) 3.0 (2006):

deaf-aid
    n 1: an electronic device that amplifies sound and is worn to
         compensate for poor hearing [syn: hearing aid, deaf-
         aid]