TOP NEWS and HEADLINES in August

  • Prevalence of Hearing Loss Among US Adolescents Has Increased Significantly, Says Survey
  • Panasonic Digital Hearing Instruments Debut in US Marketplace
  • Tinnitus Practitioners Assn (TPA) Features Education for Audiologists
  • ReSound’s Alera Wireless Hearing Aid Introduced
  • GenVec, Novartis Ink Deal To Develop Hearing Loss Treatment
  • William Demant Posts Double-Digit Growth
  • MED-EL’s Amade Audio Processor Receives FDA Approval
  • First-Ever Genetic Link for Perrault Syndrome Established
  • Westone Reformulates Silicone Singles and Pink Silicast
  • Robert Galambos, PhD, Pioneer in Neuroscience, Dies at 96
  • Scientist Believes What You Can’t Hear Can Hurt You
  • IHS and ADA to host annual conventions in Orlando and San Antonio, respectively. The International Hearing Society (IHS) will hold its 59th annual convention in Orlando, Fla, on September 29 to October 2. IHS reports that the event is “a must-attend for savvy hearing healthcare practitioners who want to excel at their chosen profession.” The convention features continuing education credits, new products and services, networking opportunities, and innovative ideas in the field. For more information, see last month’s HR Online News and the special IHS Preview section in this issue, or visit www.ihsinfo.org.

    Another vital industry event, the Academy of Doctors of Audiology (ADA) Convention, will be held November 4 to 6 in San Antonio, and feature “Ideas So BIG Only Texas Can Hold Em”, according to the Academy. ADA also reports that this year’s convention schedule has been expanded to ensure opportunities for networking and fun, without sacrificing the educational programming for which it is known.

    The ADA 2010 Convention is designed for audiologists involved or interested in autonomous practice (regardless of practice setting), and will feature sessions that offer practical business knowledge and clinical education with an strong focus on providing business tools you can implement immediately, hands-on training, and skills to enhance patient care. Topics fall into four main categories: 1) Practice Development/Business Tools; 2) Diagnostic/Biomedical Research; 3) Amplification/Rehabilitation/Counseling; and 4) Professional/Advocacy/Legal/Ethical Issues. For more information, visit look for next month’s ADA Preview in HR or visit www.audiologist.org.

  • Hearing aid sales up slightly in first half of 2010. According to Hearing Industries Association (HIA) statistics, US net hearing instrument sales increased by 2.93% to 686,165 units during the second quarter of 2010; however, private sector unit sales (ie, disregarding VA dispensing activity) increased by only 0.97%. These figures represent a slight deceleration from the first quarter, when unit volume growth was 5.51% and 2.74%, respectively. When comparing the first half of 2010 to 2009, unit sales for this year increased by 4.17% overall and 1.84% for the private sector. VA dispensing activity has continued at a brisk pace, with unit volumes increasing by 14.96% in the second half on top of 25% gains in the first half of 2009.

  • Apple's iPhone 4
    Apple’s iPhone 4
  • More hearing-related applications becoming available. Apple and AT&T have partnered with The Z, Clearwater, Fla, makers of ZVRS, to bring video relay calling to deaf and hard-of-hearing users via the iPhone 4 and its FaceTime video chat functionality.

    ZVRS is designed to allow hard-of-hearing and speech-impaired people to communicate with hearing people in real time, via a sign language interpreter. Using an iPhone 4 with a real-time video connection, an interpreter “relays” the conversation between the two parties: voicing what the deaf person is signing to the hearing caller and translating the spoken words into American Sign Language (ASL) for the deaf/hard-of-hearing caller to see. In addition to hardware, ZVRS makes video relay software for both Macs and PCs. With the help of Apple and AT&T, it has brought its latest software, dubbed iZ, to the iPhone 4. iZ was released July 26 to coincide with the 20th anniversary of the Americans with Disabilities Act.

    Apple previously touted the ability of the iPhone 4 and FaceTime to help people who speak through sign language to communicate with one another. The iPhone 4 has two built-in cameras, one on the front above the display and one on the back next to the LED flash. The front camera has been tuned for FaceTime and reportedly has just the right field of view and focal length to focus on the user’s own face at arm’s length. Apple released a commercial in early June for this feature that included two people signing to one another via the iPhone 4 and FaceTime.

    An application called Sign 4 Me assists beginners with an interest in American Sign Language who own an iPhone, iPad, or iPod touch. With this $9.99 application, you control a 3D animated character that demonstrates ASL with a library of over 11,500 words. Text in the word, and it reportedly shows you the sign.

    A $1.99 application called Sound Amp R is designed as a pocket amplifying device. Also functioning on the iPhone, iPad, and iPod touch, it uses the devices’ built-in microphone or headset with mic to amplify nearby sound. Users can adjust the volume, frequencies in five bands, and background sound levels one ear at a time.

    As previously reported in HR’s online news and our weekly enewsletter The Insider, Unitron offers its 99-cent uHear, a self-administered screening application designed to identify potential hearing loss through three assessments: hearing sensitivity, speech in noise, and a questionnaire about common listening situations. According to the company, it is a sophisticated and comprehensive test with real-life results, calibrated to test actual hearing thresholds and calibrated for both ears. It also offers a locate function to help find the nearest hearing care professional for a full follow-up. The proceeds from uHear sales are donated by Unitron to hearing-related charities.

  • Imaging research shows how the brain can fail to tune out tinnitus. About 40 million people in the United States are reported to have tinnitus. Now, new research suggests there may someday be a way to alleviate the sensation of this sound, says Josef P. Rauschecker, PhD, a neuroscientist from Georgetown University Medical Center, and his colleagues in the June 24 issue of Neuron.

    Tinnitus has been compared to the “phantom pain” felt in an amputated limb, as it often starts with damage to hair cells in the cochlea of the inner ear. This damage forces neurons in the brain’s auditory areas, which normally receive input from that part of the cochlear, to become overactive and fill in the missing sound. That extra, unreal noise is normally inhibited—or tuned out—by a corrective feedback loop from the brain’s limbic system to the thalamus, where all sensory information is regulated, before it reaches the cerebral cortex, where a person becomes conscious of the senses. But that doesn’t happen in tinnitus patients due to compromised brain structures in the limbic system.

    “Neurons, trying to compensate for loss of an external signal, fire to produce sound that doesn’t exist in tinnitus patients, just like neurons send pain signals to someone who has lost a limb,” Rauschecker says. “What both … have in common is that they have lost the feedback loops that stop these signals from reaching consciousness.”

    Rauschecker said this conclusion, from his research and from other leaders in the field, provides the first testable model of human tinnitus that could provide some new avenues for therapy. “If we can find a way to turn that feedback system back on to eliminate phantom sound, it might be possible one day to take a pill and make tinnitus go away,” he said.

    Rauschecker collaborated with coauthors Amber Leaver, PhD, a researcher in his laboratory, and Mark Muhlau, a neurologist from the Technische Universität in Munich, Germany.

    Tinnitus can be caused by damage to hair cells from a loud noise or from neurotoxicity due to medications, he noted, but more often than not, it is associated with hearing loss in some frequencies that commonly occurs as people age. Research into tinnitus is changing the common understanding of the disorder. “It has long been thought, and still is believed by many today, that tinnitus is a problem only of damaged hair cells in the inner ear, and if those hair cells are restored, tinnitus goes away,” says Rauschecker.

    However, the latest research suggests that, while tinnitus may initially arise from such peripheral damage, it becomes a problem in the brain’s central auditory pathways, which reorganizes itself in response to that damage. Recent animal models have corroborated this explanation, but have not provided a conclusive answer to the location and nature of these central changes. That led neuroscientists to employ a whole-brain imaging approach, utilizing neurophysiological and functional imaging studies, to visualize various regions of hyperactivity in the auditory pathways of tinnitus patients.

    The model that Rauschecker and his coauthors now propose is that receptors in the auditory region of the brain that do not any longer perceive sensory input from damaged hair cells compensate by firing spontaneously and frequently, producing the initial tinnitus signals. “Like phantom pain, the firing of central neurons in the brain continues to convey perceptual experiences, even though the corresponding sensory receptor cells have been destroyed,” he said. “The brain fills in sensations in response to a deficit of input. Neighboring frequencies become amplified and expand into the vacated frequency range. It also happens to people with a hole in their retina. They don’t see the hole because the brain fills in what is missing.”

    Imaging studies further show hyperactivity not only in auditory pathways of the cortex and thalamus but also in the nonauditory limbic brain structures that regulate a number of functions—including emotion. This limbic activation has been interpreted to reflect the emotional reaction of tinnitus patients to phantom sound, but research has now shown the limbic region normally blocks sound sensations sent from the auditory region that are not real. It does this by feeding sensations of sound that are not real back to a brain area in the thalamus (the thalamic reticular nucleus) that exerts inhibition on the sensory signals and can thus subtract the errant noise.

    “This circuit serves as an active noise-cancelation mechanism—a feedback loop that subtracts sounds that should not be there,” says Rauschecker. “But in cases where the limbic regions become dysfunctional, this noise-cancelation breaks down and the tinnitus signal permeates to the auditory cortex, where it enters consciousness.” Researchers have also found evidence that this inhibiting gating mechanism can be switched on and off, which explains why some tinnitus patients have a ringing sensation intermittently.

    It remains unclear, however, why some individuals who have hearing loss do not develop tinnitus. “Given that some people with tinnitus seem to be more susceptible to other disorders like chronic pain and depression, it could be that they have an independent systemic vulnerability in one or more neurotransmitter systems in the limbic region,” Rauschecker said. “That could explain why drugs that modulate neurotransmitters, like serotonin, appear to help some people out.”

    Insomnia is also linked to tinnitus, and not because ringing in the ears keeps patients awake, Rauschecker says. “Insomnia may cause tinnitus, and both may be related to serotonin depletion,” he says. “It appears tinnitus is the auditory symptom of an underlying syndrome, which becomes evident in patients who happen to have a hearing loss,” he said. Therefore, the authors contend that identification of the transmitter systems involved in the brain’s intrinsic noise cancellation system could open avenues for drug treatment of tinnitus.

    The research was supported by the National Institutes of Health, the Tinnitus Research Consortium, the Tinnitus Research Initiative, and the Skirball Foundation.

  • Hearing loops making news. A news story featuring audiologist Linda Reminsnyder about hearing loop systems has been bouncing around established and popular media sources for the past several months. The Hearing Loss Association of America (HLAA), Bethesda, Md, spotted the embedded video on YouTube featuring a Chicago ABC Channel 7 news story about audio loops in churches. (See the original ABC video and article by Karen Meyer.) A recent article in the Chicago Tribune, “Churches Putting Hearing-Impaired in the Loop,” also notes that a dozen houses of worship in the city have installed loop systems for the benefit of worshippers.

  • Key mechanism in sound localization discovered. Researchers at New York University say they have identified a mechanism the brain uses when performing sound localization. Their findings, which appear in the journal PLoS Biology, focus on how the brain computes the different arrival times of sound into each ear to estimate the location of its source.

    Animals can locate the source of a sound by detecting microsecond (one millionth of a second) differences in arrival time at their two ears. The neurons encoding these interaural time differences (ITDs) receive a message from each ear. After receiving these messages, or synaptic inputs, they perform a microsecond computation to determine the location of the sound source. The NYU scientists found that one reason these neurons are able to perform such a rapid and sensitive computation is because they are extremely responsive to the input’s “rise time”—the time it takes to reach the peak of the synaptic input.

    Existing theories have held that the biophysical properties of the two inputs are identical—that is, messages coming from each ear are rapidly processed at the same time and in the same manner by neurons. The NYU researchers challenged this theory by focusing on the nature of the neurons and the input—specifically, how sensitive they are in detecting differences in inputs’ rise times and also how different these rise times are between the messages arriving from each ear.

    Buoyed by predictions from computer modeling work, the researchers examined this process in gerbils because the animals process sounds in a similar frequency range and with apparently similar neuro-architecture as humans. Initial experimental findings were obtained by examining the gerbils’ neuronal activity and by directly stimulating the synaptic pathways. They found that the rise times of the synaptic inputs from the two ears occur at different speeds: the rise times of messages coming from the ipsilateral ear are faster than those driven by the contralateral ear. Thus, the brain has two groups of neurons that do computations in each brain hemisphere, with ipsilateral messages coming from the same-side ear and contralateral messages coming from the opposite-side ear. In addition, they found that the arrival times of the messages from each ear were different.

    Results obtained using a computer model showed that neurons perform the location computation differently than what neuroscientists had previously proposed; neurons not only encode the coincidence in arrival time of the two messages from each ear, but they also detect details on the input’s shape more directly related to the time scale of the computation itself than other features proposed in previous studies. “Some neurons in the brain respond to the net amplitude and width of summed inputs—they are integrators,” explained Pablo Jercog and John Rinzel, two of the study’s coauthors. “However, [other] auditory neurons respond to the rise time of the summed input and care less about the width. In other words, they are differentiators—key players on the brain’s calculus team for localizing a sound source.” The study’s other authors were Dan Sanes, Gytis Svirskis, and Vibhakar Kotak – read the article here.


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