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The Latest in Hearing Aid Technology
From: ENT Today, March 2009
by Heather Lindsey
Open-ear fittings, wireless connectivity, and advances in computer chip circuitry are some of the recent advances in hearing aid technology that can make the devices more user-friendly and improve sound quality.
Numerous models of high-technology hearing aids are available, but the majority of them are similar to one another, said Catherine Palmer, PhD, Associate Professor in the Department of Communication Science and Disorders in the University of Pittsburgh's School of Health and Rehabilitation Sciences and an audiologist at the University of Pittsburgh Medical Center.
There's no one best hearing aid, she said. There's the best hearing aid for a specific person. The choice is individualized.
Audiologists may also decide to work with particular models based not only on their technology levels but also on their repair rates and customer service, added Dr. Palmer.
Open-Ear Hearing Aids
One of the newest and most important changes in hearing aid technology is the development of devices that leave the ear canal open, said Dr. Palmer.
For years, audiologists took an impression of the outer ear and ear canal to custom-fit the hearing aid, but these models blocked low frequencies, sometimes causing occlusion, explained Carolyn Barton, AuD, Manager of the Hearing Aid Dispensary at the North Shore-LIJ Health System in New Hyde Park, NY. Open-ear fittings are small, sleek, and discreet and fit behind the ear (BTE), leaving the ear canal relatively unoccluded, except for a thin wire or tube, she explained.
Some open-ear models rest in the concha and come in many designs that are almost worn like ear jewelry, noted David B. Hawkins, PhD, Professor of Audiology at the Mayo Clinic in Jacksonville, FL.
Whether a BTE or concha device, the unit houses the microphone, digital circuitry, amplifier, and battery, explained Dr. Barton. If it also contains the speaker or receiver, sound is delivered to the patient via a thin tube running from the device to the ear canal. Alternately, speakers can sit directly in the ear canal and are connected to the BTE or concha unit via a small wire.
Some audiologists originally thought that having the receiver in the canal (RIC) would create less feedback because it is further away from the microphone, noted Dr. Barton. Additionally, they thought the wires might provide better sound quality because of the resonance of the thin tube. [However,] we are not really seeing much of a difference between the two, she said. They are both premium products that come with a number of advanced technological features, she explained.
RIC models sometimes may be more prone to damage from cerumen or moisture than models with both receiver and microphone in the main body, noted Daniel H. Coelho, MD, Assistant Professor of Otolaryngology-Head and Neck Surgery at Virginia Commonwealth University School of Medicine in Richmond. However, RIC devices allow more power or volume to be delivered, and, consequently, more patients with worse hearing can be fitted, he added.
Generally, open-ear hearing aids may provide users with mild to moderate high-frequency hearing loss with high-frequency information that help clarify speech and provide localization cues, explained Dr. Barton.
Most high-end hearing aids are also able to communicate with each other via wireless technology, said Dr. Hawkins. If a patient changes the settings on one hearing aid, the other will automatically adjust, he said. If one hearing aid automatically adjusts to sounds coming from the patient's environment, the other will change to coordinate how they both amplify together.
Moreover, most major hearing aid companies are now able to connect their products to Bluetooth technology via a gateway device that is about the size of an iPod and is worn around patients' necks so they can better hear their TVs, computers, and telephones in both ears, said Dr. Hawkins. The Bluetooth receiver is not small enough to package within the hearing aid itself, he added.
Because Bluetooth technology is generally short-range, patients don't have to worry about other wireless devices interfering with sound transmission, said Dr. Coelho.
Advances in Circuitry, Algorithms, and Directional Microphones
Another big change to occur over the last five to seven years has been in hearing aid circuitry design, said Dr. Hawkins. Computer chips can now amplify sounds in several different ways, adapting to how loud a room is and whether speech and/or noise are present, he explained.
For example, most mid- to upper-level hearing aids will automatically amplify sound differently when patients are watching television in a quiet room than when they are dining in a loud restaurant where background noise is a problem, explained Dr. Hawkins.
Automated speech enhancement and noise reduction algorithms complement directional microphones, making it more comfortable to hear through noise, said Dr. Barton. Although not new, directional microphones are steadily improving and helping to increase the signal-to-noise ratio. Hearing aids are able to find multiple points where noise is coming from and then create a null point to help control the problem, she explained.
New advances in circuitry also help to reduce environmental sounds, such as wind, without sacrificing speech intelligibility, said Dr. Coelho. This is ideal for someone who spends a lot of time outside, he said.
Technology also allows hearing aids to achieve more amplification before an individual is bothered by feedback, noted Dr. Palmer. Feedback has been one of the challenges frequently associated with open hearing aid systems, she noted.
No automatic chip does what the patient wants it to all the time, noted Dr. Hawkins, so hearing aid models have an override option. Hearing instrument companies are working on refining their algorithms for these automatic settings, he added.
Type of Hearing Aid Is Individualized to the Patient
While open-ear devices have their benefits, they are not for everyone, noted Dr. Palmer. Decisions on what style is best for a particular patient depends on audiometric results and the individual's specific communication needs, demands, and lifestyle, she said.
For example, someone who is outdoors a lot may need a water-resistant device, said Dr. Palmer. Additionally, people who are physically active may not want BTE devices because they are afraid of having them knocked off, she said. In these cases, a hearing aid that fits completely in the ear canal (CIC) may be a better option, she said.
One drawback of CIC hearing aids is that they cannot house directional microphones because of how small they are and where they sit in the ear, said Dr. Barton. However, an advantage of the device is that less power may be needed because it requires a potentially deeper fitting near the tympanic membrane, and the concha is open and resonates, increasing the high-frequency input to the hearing aid microphone, she explained.
Collaboration Between Otolaryngologists and Audiologists
In today's health care and reimbursement environment, otolaryngologists may have little time to talk to patients about their many hearing aid options, noted Dr. Hawkins. The ENT can encourage patients to pursue hearing aids and work with a good audiologist, he said.
Overall, a good working relationship between otolaryngologists and audiologists is absolutely critical to providing the best care for patients and their hearing needs, according to both Gregory Artz, MD, Assistant Professor in the Department of Otolaryngology at Jefferson Medical College of Thomas Jefferson University, and Nancy Catterall, AuD, F-AAA, Director of the Jefferson Balance and Hearing Center at Thomas Jefferson University Hospital in Philadelphia.
Both specialists can give patients different, complementary information that will help them make an informed decision regarding hearing aids, they jointly wrote in an e-mail. While the otolaryngologist is best positioned to provide medical-surgical care, the audiologist is the expert when it comes to counseling, recommending, and fitting hearing instruments, especially high-tech digital products. Correctly counseling patients based on their hearing loss so they have realistic expectations is also crucial, they noted.
What Patients Need to Know
Patients are often confused about their options and the differences between hearing aid technologies, said Dr. Palmer.
Moreover, many patients have an outdated perception of hearing aids based on both functional and cosmetic limitations and are happy to learn that today's devices are considerably different from the kind they might have seen their grandmother wearing, said Dr. Coelho.
Although hearing aids are improving, patients should understand that they still don't provide normal hearing, said Dr. Hawkins.
Patients also need to be comfortable with technology to make the newer models a success, noted Dr. Hawkins. Most baby boomers have learned how to use computers and readily adjust to newer hearing aids, whereas older people in their 70s, 80s, and 90s sometimes don't adapt as well to using the more advanced devices, he explained.
Because hearing aids are usually not covered by insurance, patients should also understand a basic pricing structure, which often includes two- or three-year service packages, said Dr. Hawkins. Prices generally range from $1300 to $1400 per ear for lower-end models, about $1800 per ear for middle-range models, to about $2500 per ear for more advanced high-end models.
Two Unique Approaches to Hearing Aids
Two new products appear to be taking a unique approach to hearing aid technology.
The Lyric (InSound Medical, Newark, CA) is a continuous-wear hearing aid designed for moderate to severe hearing loss. An audiologist or otolaryngologist places the device completely in the ear canal only 3 or 4 mm from the eardrum.
Patients really never have to touch it, and it's basically invisible, said Michael Scherl, MD, an otolaryngologist who consulted in the development of the product and who has offices in Englewood and Westwood, NJ, and in New York City. Users can turn the device on and off and raise the volume using an external magnet, he explained.
Lyric can remain in the ear for up to 120 days at a time. An audiologist replaces the device every few months when the battery dies. Battery life varies less according to power and more according to the amount of moisture and cerumen in the ear, said Dr. Scherl, who has been paid as a consultant to InSound and holds equity in the company.
Users don't buy the devices outright; rather, they pay for yearly subscription that is roughly $2900 to $4000 for both ears, said Dr. Scherl.
The sound quality is good because the device takes advantage of the natural shape of the ear canal, he explained. Additionally, patient satisfaction is high once the device is properly fitted.
Some fittings are easy and some can be time-consuming for both the audiologist and the physician, noted Dr. Scherl. Fittings can sometimes take up to a month of adjustments. There are only four sizes, although a fifth size will be available soon, and they often don't fit in narrow ear canals, he explained.
Another new hearing aid called Clik (Ear Technology Corp., Johnson City, TN) will be launched this month. It is a high-end digital hearing aid that allows the provider to fit the device without connecting to a computer or cables and doesn't require learning new software. All programming is onboard the hearing aid processor, said Daniel Schumaier, PhD, President of Ear Technology Corporation.
Patients can wear the open-fit device and make adjustments to the amplification in their own real-life noisy and quiet environments. The user can select programs for different listening situations by pressing a push button on the hearing aid. Clik also has directional microphones and twin telecoils, oriented for optimum use with loop induction systems, as well as the telephone.
An advanced programming mode is also available to the audiologist to further refine sound quality, he explained. Fifteen different programs to adjust frequency response allow for this fine-tuning.
Dr. Schumaier anticipates that the provider cost of the Clik will be substantially less than that of other high-end hearing aids on the market, because the device does not require computer hardware and software for programming or the high levels of technical support required in the traditional digital hearing aid business model.
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