Fully Implantable Hearing Device
Many hard of hearing people would prefer to go without normal hearing aids. These people may participate in swimming and fear the water will harm the device. Or there might be worries about the device’s ease of use while sleeping.
Otologics has developed a new kind of hearing aid that will overcome these problems. The device is implanted in the user’s middle ear and uses a microphone to pick up sound signals, which are then processed by electronics. From there, it is sent to a piston against the small bones in the middle ear, which then transmits the vibrations to the inner ear. The inner ear encodes these vibrations as nerve impulses and sends the information to the brain. This method works because it sends sound directly to the cochlea.
This means a chance at a normal life for hard of hearing people. “You can be exposed to environments in which hearing aids have difficulty operating properly”, says Otologics’ CEO José Bedoya.
The challenge in manufacturing a device to implant is to design one that works well under the skin. Mr Bedoya explained that human skin changes throughout the day due to hydration levels and other factors.
The device charges by putting the charger coil on the spot where the implant was made. The average charging time is about one hour each day and the wearer can carry on with normal activities while it charges. The battery lasts for at least five years, after which it needs replacing. The components are sealed together to protect against leaks, so everything except the piston would have to be replaced.
The hearing aid’s phase I clinical trial in 2007 implanted aids into twenty subjects’, who all had moderate to severe hearing loss. The subjects all had slightly worse hearing than with their old hearing aids for the duration of the study, but their satisfaction levels were up. Even though their word-recognition scores dropped by 20 per cent, they felt that the device improved their hearing by making it sound more natural.
There are experts who doubt whether Otologics’ implant is a big improvement. The cost may be prohibitively high. The cost is $19,000 in Europe for the implant alone, while it costs $6,000 for a high-end conventional aid. This implantation device is still in clinical trials in the United States. Another critic, Gerald Loeb, who is a professor of biomedical engineering at the University of Southern California, would prefer implanted hearing aids to outperform conventional ones. Only then, he reckons, would they be worth the extra cost and risk.
He asked an important question: “How big an issue is it to have a little appliance on your ear when the whole world is walking around with cell-phone headsets and iPod earpieces?”
Other experts see great progress being made in implantable microphone design. Joseph Roberson, who is an ear surgeon and the CEO of the California Ear Institute, says, “I listened to a good-fidelity musical signal received by an implantable microphone positioned under half an inch of raw steak.” The functional outcome of the Otologics device, he says, is “roughly equivalent to existing visible external technology.”
However, the phase I study revealed that the Otologics hearing aid technology “serves as a viable treatment alternative for moderate to severe sensorineural hearing loss.” Bedova’s company is addressing the problems found and is preparing for phase II trials. The second trial will test 90 subjects with a revised device.
It seems ‘alpha adopters’ may be the ones most suited to this type of device. Roberson thinks they “are motivated to keep their use of a hearing device a private matter, or those who are intolerant of standard hearing-aid technology.”