Researchers at UC Irvine are developing a new breed of hearing implants that will reshape the landscape of auditory technology. The research has already been met with spectacular results on a global scale.
Cochlear implants detect external sound waves and translate them into signals that are relayed though tiny electrodes. These electrodes connect directly to auditory nerves, which in turn lead to the brain. They differ fundamentally from traditional hearing aids, which only amplify sound.
“[The cochlear implant] is essentially an electronic device that replaces the damaged microphone function in the human ear,” said Dr. Fan-Gang Zeng, director of the Hearing and Speech program at UC Irvine. “In a hearing aid, sound goes in and sound comes out. But in a cochlear implant, sound goes in and electric signals come out.”
The theory behind the implants has been well-established for decades. But only recently have researchers begun to engineer and fine-tune them with such precision.
“The concept of cochlear implants started back in the 1950s,” said Dr. Hamid R. Djalilian, director of the Neurotology and Skull Base Surgery at the UC Irvine Medical Center. “The first cochlear implant device was implanted in the 1970s. The device was FDA approved in 1984 … and starting in the mid 1980s cochlear implants have been performed at UC Irvine.”
Neuroscientist Dr. John Middlebrooks recently joined the research team to help decipher how the brain responds to the implants. “I look at optimal ways to stimulate them to transmit speech information,” Middlebrooks said, “and I‘m also working on a novel kind of electrode that might be the next generation of the auditory prosthesis.”
These advancements in auditory technology have benefited scores of patients, many of whom have resumed normal auditory tasks.
“One of our patients used to be a musician,” graduate student and researcher Janice Chang said. “But then he suddenly lost his hearing. He was implanted about two years later, and his wife convinced him to pick it up again. It’s amazing; he can tune his guitar through his cochlear implant.”
Fellow graduate researcher Payton Lin was taken aback when he first met one of the beneficiaries of his research.
“When you first meet cochlear implant patients and communicate with them, often times you’ll forget that they have some kind of hearing deficit,” Lin said. “I thought I would have to repeat myself or talk slowly. But a lot of times, I’m just talking at a normal speed and they pretty much pick up everything.”
While most of their research focuses on cochlear implants, some of these students work to create implants that are hybridized with hearing aids.
“I try to optimize a combination of cochlear implants and other devices to improve speech intelligibility for our subjects,” graduate researcher Hsin-I Yang said.
One of the determinative factors in cochlear implantation is the age of the subjects. Young children tend to have better post-implantation results since they are still in the language development phase of their lives.
“There is a time window during which they can get an implant and learn to speak,” Djalilian said. “From the ages of two to four, that ability diminishes a little bit. And by age nine, there is zero chance that they will learn to speak properly. So it’s really important that they get recognized and evaluated early.”
Although his research focuses primarily on the human ear, Zeng noted that the technology could be much more far-reaching.
“Once you can simulate a nerve using this device, you can put it anywhere. If you can stimulate the hearing nerve, why can’t you stimulate the visual nerve so we can restore vision to blind people?” Zeng said. “We’re working along those lines … to develop neuron technology, which has a wide range of applications.”
The team of researchers is also trying to refine the device to help deaf people regain the ability to listen to music. They are also trying to lower the cost of the procedure so that it will be financially accessible to more people. They are hopeful that it will one day change the way deafness is treated.
“My goal is to make the implant as safe and effective as possible,” Middlebrooks said. “And I’m optimistic that the penetrating auditory nerve implant will be a substantial improvement.”