A hearing aid has a housing which can be worn at the head, such as in or behind the ear, and which contains the basic electrical and acoustic elements of the hearing aid. The housing has a portion adapted for introduction into the auditory canal, and a cover, both of which are electrically conductive...http://www.google.de/patents/US4918737?utm_source=gb-gplus-sharePatent US4918737 - Hearing aid with wireless remote control
