New Cochlear implant on leading
edge for hearing-impaired.
Courtesy of the
Hearing Foundation of Canada
For some deaf people, the cochlear implant offers a new world of sound and conversation.
A sophisticated ear implant has given Toronto business lawyer John Humphreys a new world of sound and conversation to experience.
Humphreys, who was born with profound hearing loss, cause unknown, underwent surgery for a cochlear implant at Sunnybrook Health Services Centre in Toronto last summer. "It’s been a tremendous leap forward," he said.
"I am hearing sounds I’ve never heard before. I’m having conversations with people without having to lip-read, and I’m even enjoying some telephone conversations with a minimum of repetition."
The cochlear implant is a procedure that involves opening the scalp and drilling near the brain in order to implant electrodes into the inner ear, and create a direct source of electrical stimulation to the auditory nerve of the brain.
"It’s a brand new way of listening to sound," said Humphreys, who works at the law firm of McCarthy Tetrault of the 50th floor of the Toronto Dominion Centre in Toronto. He was called to the bar in 1998, and has been working at the firm since that time.
"It affords a much wider ability to listen, compared to the acoustic amplification of conventional hearing aids," he said.
Humphreys, who speaks in a soft, modulated voice that he developed as a result of seven years of speech and auditory therapy during childhood, said he underwent seven months of auditory therapy after the implant. Both he and his therapist are amazed at his progress.
"Technological developments have been a tremendous boon [for hearing impaired people]," he said, citing technological changes in communication through the Internet, by e-mail and on-the-computer conversations via Yahoo and ICQ. These have made communication much easier for hearing-impaired people, he said, but the cochlear implant is by far the most exciting advance.
The implant is designed for people who are profoundly deaf, who have no function in the inner ear, said Dr. Robert Harrison, a professor of otolaryngology at the University of Toronto and a senior scientist at the Hospital for Sick Children, where implants in children are performed.
Dr. Harrison, who started and directed the cochlear implant program at the Hospital for Sick Children 12 years ago, said the devices bypass the defective inner ear, "and stimulate the brain directly."
A small electronic device is totally implanted into the skin to deliver small electrical currents to stimulate the nerves, he said. There’s also an external device, consisting of a microphone to take in speech signals and other environmental sounds, which is worn behind the ear. It sends the signal to a speech processor worn like a small pack on the body. Adults wear it on a belt pack; children are usually fitted with a special sling for the processor, he noted.
The majority of adults fitted with a cochlear implant have had some hearing. Most of the children who undergo the implant are "congenitally deaf," he said. "They are deaf from birth, and have never had any hearing."
"We’re doing cochlear implants on children of two years of age, and in the future, we’re likely to be doing this on even younger children," Dr. Harrison said. "The earlier one provides some hearing to an infant the better that child will hear in the future. It’s all to do with the business of needing to stimulate the brain at a very early age, because the actual auditory stimulation helps to develop the hearing pathways in the brain."
The cochlear implant, he said, has been around for 25 years. "The very earliest versions of cochlear implants were very primitive. The earliest devices were a single electrical wire stimulating the inner ear, and they weren’t able to carry much information, because it was just one channel."
"The newer devices have a number of electrodes that stimulate different parts of the auditory nerve, and we have the ability to input a lot more information with them."
The cochlear implant device costs about $20,000 and is covered either by OHIP or special funding for cochlear implant programs in Ontario. About 50 children a year are implanted at the hospital. Another 70 adults a year are implanted across the province, in Toronto at Sunnybrook.
"We’re implanting more adults because more people are learning about the cochlear implant, and more older people are coming for it. A lot of older people, as they lose their hearing and can’t use a hearing aid, are becoming candidates."
The implants, though, do not restore normal hearing, he cautions. "The sounds are very unusual, like tuning into a radio station but it’s not quite at the right wavelength," he said. Some of the new sounds created by the implant are distorted. Some describe the speech they hear to be like that of a cartoon character, he added.
"But many are very impressed with what they do hear," he said. "And we are very encouraged that everyone improves their understanding of speech with the device... I would say this is really the leading edge in technology for sensor prosthesis."
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