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Hearing aids, cochlear implants and hearing loops

Published on: August 20, 2014

By LIA MARTIN

The cochlea in the ear, with damaged hair cells.

The cochlea in the ear, with damaged hair cells.

There are still many things we don’t know about how the ear works. How do we hear, and how do we lose our hearing? Some are born deaf, or become deaf over time because of a genetic abnormality. Damage to the ear can occur because of a loud noise such as an explosion or a loud recurring noise over time, causing deafness. Viral infections of the inner ear and auditory nerve also can cause deafness. Diseases, such as Meniere’s disease, acoustic neuroma, meningitis, encephalitis, multiple sclerosis or stroke can also cause deafness.

However, the biggest single cause of deafness is age-related hearing loss, or presbycusis. By 30 to 40 years of age, most people begin to lose some hearing. By 80 years of age, most people will have a significant hearing problem.

The reason for age-related hearing loss is simple. The hair cells inside the cochlea, which is the hardest bone in the body, gradually become damaged. High-frequency sound such as a female or child’s voice may become hard to hear. Background noise  may make hearing more difficult.

In short, sound waves are funneled into the ear so that the ear drum vibrates. The vibrations are transmitted to the cochlea in the inner ear because of three small bones. Rows of inner and outer hair cells line a part of the cochlea. The sound waves amplified by the outer hair cells vibrate the inner hair cells opening the ion channels, which allow neurotransmitters to flow in. This triggers electrical impulses in the cochlear neurons, and the information is passed to the brain.

These inner and outer hair cells become damaged as we age. It is thought that past age 25 we experience a real reduction of hearing at higher frequencies.

Scientists are developing new tests and technologies that  could “grow back” hair cells. In 2013, they discovered that certain genes could transform the cells supporting the hair cells. An Atoh1 gene was inserted into a harmless virus and was injected into the cochlea of mice by University of Kansas Medical School scientists. Two months later, it was estimated that there was a 20 percent decibel increase in the hearing of the mice.

Currently, scientists at the school will be conducting a human study using the technology used on the mice. They will choose around 45 volunteers between ages 18 and 70 who will begin using the Atoh1 technology. This group would have severe hearing loss, but could not be deaf from birth. Other criteria will be needed to establish a good test group.

Brian Applegate, Texas A&M Department of Biomedical Engineering professor, also thinks the new studies are bringing a real understanding of the inner ear and how to fix it. He thinks that there is such little knowledge about the inner ear because they have not had detailed photographs of that small area within the cochlea.

Applegate and his team have managed to take images of that area with new technology they developed so that headway can be made in understanding how to repair damage within the inner ear as it pertains to hearing loss.

“The points of our research are to better understand hearing, to learn more about the actual morphology of the inner ear as well as how it processes vibrations,” Applegate  says. “We also want to understand how different pathologies affect the ear. We want to know what happens when a person has progressive hearing loss due to loud sounds, traumatic injury or even genetic mutations. We want to see how these things change the soft tissue in the ear.”

Other scientific studies have expanded our understanding of hearing and how noise frequency contributes to hearing.

In 2005, Howard Stapleton invented a device he called the Mosquito alarm, which is an electronic alarm that can only be heard by people younger than 25 years old. The controversial product has been used commercially to reduce loitering, drug use and violence by teenagers in areas where retailers experience business losses because unruly teens drive away business.

Teens took this technology knowledge one step further and found they could program their cellphones with a higher frequency ring tone that could not be heard by their teachers in the classroom.

Outside of restoring hearing, a hearing aid was the first solution developed by scientists to help age-related deafness. The solution was hard to use because background noise would cloud hearing when someone was speaking from across the room. Many of us can remember our dads or granddads fiddling with their hearing aids, so it is little wonder that only one in five who could use a hearing aid will actually use one.

Now, with digital technology and mini-microphones, hearing aids offer a new experience. Hearing aids can now filter out background noise, clean up the sound quality and be computer programmed to match the nuances of each person’s hearing loss. The aids also are tiny and almost invisible.

Cochlear implants are now available for some who have hearing loss, whether they are children or seniors in their 80s. A cochlear implant is an electronic medical device that bypasses damaged hair cells in the cochlea and stimulates the remaining nerve fibers directly with an electric current. A good candidate for an implant would be a person who cannot understand speech without seeing a person’s face. Cochlear implants have an internal and external component. The internal component is surgically inserted behind the ear, and a narrow wire is threaded into the inner ear. The cost of the implant is also covered by Medicare.

For hearing aid and cochlear implant users alike, hearing loop technology has brought a real boon in hearing. This technology is equipped in rooms, such as meeting rooms, churches, operas and theaters. A hearing loop is a wire that encircles a room and is connected to a sound system. The loop transmits the sound electronically to the hearing aid or implant and is picked up when you flip on the T-switch of the hearing aid or cochlear implant to activate the telecoil.

To learn more about what can be done to counteract hearing loss, Hearing Loss Association of America, Sun City Center, has an educational event at its next chapter meeting starting at 9:30 a.m. on Wednesday, Sept. 3, at St. Andrew Presbyterian Church, 1239 W. Del Webb Blvd., Sun City Center.

Retired otolaryngologist Dr. Lindsay Pratt will give a talk on “Hearing Aids can be your best friend: Learn more about your hearing and learn how to improve your hearing and word understanding.”

Lisa Tanner Au.D will speak on “New technology available for persons with hearing loss” at the Oct. 1 meeting.

The HLAA meeting room in Sun City Center is equipped with an induction hearing loop, as are the Sun City Center Community Hall; Sun City Center Florida Room; Freedom Plaza auditorium; Beth Israel Synagogue; St. Andrew Presbyterian Church, sanctuary and Fellowship Hall; United Community Church, sanctuary and Great Hall; Publix Supermarket at King’s Crossing; Prince of Peace Catholic Church; and First Baptist Church of Ruskin sanctuary.

HLAA is a 501(c)3 non-profit organization that adopts HLAA’s mission of opening the world of communication to people with hearing loss by providing information, education, advocacy and support. HLAA is an umbrella organization and has nonprofit status. More information about HLAA is available to anyone visiting it on www.hearingloss.org. Learn more about the Hearing Loss Association of America, Sun City Center chapter at www.hlascc.com.

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