Dan Gardner M.S.
CEO Gardner Audiology
2015 Update
As of February of 2015 there have been no significant developments in middle ear implantable hearing aids.
The most common type of surgically implanted hearing aid is anchored into the skull when some type of medical condition prevents a person from wearing a conventional hearing aid. Some companies have devoted quite a bit of energy to develop a different type of hearing aid that can be implanted on the middle ear bone instead of the skull. Sound Tec was FDA approved but appears to have gone out of business. The Esteem was FDA approved in 2010. The Sound Bridge is another middle ear implant manufactured by Med El.
The middle ear bones must be disarticulated in order to implant the Esteem hearing aid. Manufacturer, Envoy Medical, proposes that it can treat up to and including severe sensorineural hearing losses implanting the devices pictured below:

The Med El Soundbridge is pictured below. Med El purchased this design from Symphonix. The middle ear bones remain intact during the implant of the Soundbridge.
