by Neil Bauman, Ph.D.
Some people have been longing for a completely implantable hearing aid. Besides the (dubious) advantage of being completely invisible (people won’t be able to tell if you are hard of hearing so won’t make allowances when you don’t hear them), there are a few real advantages to a totally implantable hearing aid.
For example, if you spend time in the water swimming or splashing around, you’ll still be able to hear. Ditto when you are in the shower. Furthermore, you can leave it on all night as you sleep so if you are a mother with young children, you’ll be able to hear them if they cry during the night (assuming you don’t roll over and sleep on the implant side so the microphone is buried in the pillow). Also, if you live in a humid location, or sweat profusely, or work in a dirty environment, all that extra moisture and dirt won’t “gum up the gearworks”. Furthermore, if wearing hearing aids/ear molds causes problems in your ear canals, with an implanted hearing aid, your ear canals will be totally free of any apparatus.
The good news is that if you are so inclined, you now can get such a hearing aid. Otologics of Boulder, CO has introduced their new fully-implantable hearing aid called the Carina.
Here’s how it works. The microphone, which is implanted under the skin, sends the sound signals to the amplifier which is surgically embedded in the mastoid bone behind your ear (much like the internal parts of a cochlear implant are embedded). The output of the amplifier is sent down a wire to a transducer (vibrator), the point of which touches, and thus pushes on, the incus (anvil), the second of the three bones in your middle ear. This mechanical motion amplifies the normal sound signal that is then sent in the usual fashion to the incus (stirrup) and from there to the inner ear.
Incidentally, the amount of movement the transducer imparts to the incus is very small—only 1 to 2 micrometers. That is only 1 to 2 thousandths of a millimeter, (or about one 25 thousandths of an inch) an imperceptible movement even under a microscope.
Since it is all internal, you need a remote control to adjust the volume and turn the hearing aid on or off. Unlike the remotes in typical hearing aids where you just hold the remote in your hand in front of you and press a button, the Carina remote has to be placed right over the implant behind your ear before you press any buttons.
The implant is programmed according to your specific hearing needs just like any regular digital hearing aid. The Carina is designed for adults with moderate to severe hearing losses.
Since the battery is also internal, the folks at Otologics had to come up with a way to recharge the internal battery. The charger system consists of the base station, a charging coil, and the charger body. To recharge the implant, you remove the charger body from the base station and place the coil on your skin over the implant. The charger body contains a clip so you can attach the charger to your belt during charging. Typically, charging time is about 1 hour. You must recharge the Carina daily. While recharging, you can go about your normal daily activities, turn the implant on and off, and adjust the volume.
One cool thing about the Carina is if the battery dies or the implant quits working for any reason you won’t be left totally deaf—you can still use your residual hearing. You see, the implant does not affect your residual hearing. Thus you could even temporarily wear a backup hearing aid in your implanted ear.
There are some downsides to implantable hearing aids. For one thing, upgrading your “hearing aid” as new technology comes along is going to be a real problem. Second, you will need surgery to replace the battery when it finally dies. This won’t happen often as the battery has a projected 20 year life span. Third, you cannot have any MRIs unless you have the whole implant surgically removed. Fourth, if you like diving or scuba diving, you will have to limit yourself to a depth of 10 feet or less. And fifth, it is pretty expensive—$12,000.00 and $15,000.00 each, and that does not include the surgery and related costs.
However, if having a fully-implantable hearing aid turns your crank, the Carina may be the hearing aid for you.
Note: On July 23. 2012, Otologics filed for bankruptcy. It appears that the Carina has gone the way of the Dodo bird and that Otologics is no more.
Good News: 2017. The Carina middle ear implant was resurrected by Cochlear Corporation and is now one of their products. You can learn more about it on this page on Cochlear’s website .