| 摘要 |
A direct contact hearing aid apparatus adapted to be mounted deep within the ear canal is disclosed, including an output electromechanical transducer for converting audio output signals into mechanical movement of an output coupling element without the production of discernible sound waves to prevent acoustic feedback. The coupling element is supported for magnetic engagement with a contact element mounted on the tympanic membrane by a metal clip attached to the malleus bone to provide direct electromechanical coupling to the ossicles through the tympanic membrane. Alternatively, the contact element may be attached to the malleus bone by a clamp whose jaws are lined with bioactive ceramic. A pair of magnetic switches is provided within the hearing aid housing for mechanically switching the connections of the battery and a volume control while the hearing aid is mounted in the ear canal in response to changes in the polarity of a remote external magnetic actuator located outside of the housing. An external magnetic attachment device is used for insertion and removal of the hearing aid, radio or other electronic apparatus into and from the ear canal by magnetic engagement with a magnetic holder member on the electronic apparatus. The magnetic attachment device may be unipolar or bipolar and has a permanent magnet which is rotated between an attraction position and a release position by a selection knob. The output transducer of the hearing aid may be a piezoelectric plastic film transducer in the form of a flexible diaphragm or a folded sheet bender of the bimorph type, or it may be an electromagnetic transducer. The electromagnetic transducer may have an external magnetic coupling element mounted outside the hearing aid housing and spaced from the magnetic core of such transducer but coupled to the contact element. Also, a reverse bias permanent magnet may be provided at the end of such core to repel a movable permanent magnet which is mounted on a resilient coupling member to form the external magnetic coupling element.
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