The invention relates to an in-the-ear hearing aid for people with impaired or defective hearing, with an ear-piece containing a microphone, amplifier, telephone, battery compartment with battery, on/off switch and volume control and closed by a cover plate; a hollow space (6) to the auricular canal...http://www.google.fr/patents/US4706778?utm_source=gb-gplus-shareBrevet US4706778 - In-the-ear-canal hearing aid
