Hearing Research

Shared Knowledge Is Power

By Lauren McGrath

Each February, thousands of hearing and balance scientists join their colleagues from around the world at the Association for Research in Otolaryngology (ARO) Mid-Winter Meeting. It is one of the premier international conferences for those in the field. I was fortunate to attend this year’s 42nd meeting, held in Baltimore, on behalf of Hearing Health Foundation (HHF), along with Emerging Research Grants (ERG) awardees past and present, Hearing Restoration Project (HRP) consortium scientists, and HHF scientific committee members—all of whom are integral to our mission to advance the prevention, treatment, and cures of hearing and balance conditions.

ARO provides auditory and vestibular researchers opportunities present their latest findings and engage in meaningful conversations with one another. If one scientist presents an idea to an audience of 100 scientists, she’s just created the possibility for 100 new ideas will form. Even one novel suggestion following a presentation at ARO can be invaluable to science.

Tenzin Ngodup, Ph.D., represents his HHF-funded tinnitus project at ARO.

Tenzin Ngodup, Ph.D., represents his HHF-funded tinnitus project at ARO.

One forum through which scientists share their knowledge at ARO is in the poster hall. ERG grantees including Tenzin Ngodup, Ph.D., and Samira Anderson, Au.D. Ph.D., stood proudly alongside large poster board displays ready to answer questions about their respective projects. Ngodup, who is currently funded by HHF and based at Oregon Health and Science University, used his poster to visually explain his progress investigating neuronal activity in the ventral cochlear nucleus (VCN) in order to prevent and treat tinnitus. “It was previously thought that there were a few hundred inhibitory glycinergic cells called D-stellate cells in the VCN, but we found a surprisingly large population of glycinergic cells— approximately 2,700—that are physiologically and morphologically distinct from D-stellate cells,” Ngodup says. By quantifying inhibitory neurons in the VCN he aims to examine inhibition in typical vs. tinnitus models, especially after noise exposure.

University of Maryland’s Anderson, a 2014 ERG grantee, represented an impressive half dozen informational poster boards with her colleagues. The titles included: “Aging Effects on the Auditory Evoked Cortical Potentials in Cochlear Implant Users”; “Mutual Information Analysis of Neural Representations of Speech in Noise in the Aging Midbrain”; and “Age-Related Degradation Is More Evident for Speech Stimuli With Longer Than With Shorter Consonant Transitions.” A clinician who transitioned to research, Anderson graciously thanked HHF for funding her first-ever scientific grant, and was thrilled to tell me her work had just been cited by the Wall Street Journal in an article called “Better Hearing Can Lead to Better Thinking,” published February 6, 2019, about the importance of hearing loss treatment in older adults.

Outside of the poster sessions in lecture halls, ARO attendees conduct topic-specific seminars to seated audiences. Elizabeth McCullagh, Ph.D., of University of Colorado Denver, a 2016 ERG grantee, led a symposium called “Mechanisms of Auditory Hypersensitivity in Fragile X Syndrome” in which she and other speakers, including Kelly Radziwon, Ph.D. (2017 ERG), and Khaleel Razak, Ph.D. (2018 ERG), presented their novel findings related to Fragile X syndrome: a genetic model for autism, difficulties in sound localization, and overstimulation by sound in mouse models.

2018 ERG grantees Joseph Toscano, Ph.D., A. Catalina Vélez-Ortega, Ph.D., and David Jung, M.D., Ph.D.

2018 ERG grantees Joseph Toscano, Ph.D., A. Catalina Vélez-Ortega, Ph.D., and David Jung, M.D., Ph.D.

Achim Klug, Ph.D., a volunteer ERG grant reviewer, remarked during the Council of Scientific Trustees (CST) reception—a gathering to formally honor our ERG 2018 grantees—how critical McCullagh’s ERG grant has been to her work as an early-career scientist. With seed funding from HHF, McCullagh was able to investigate and publish information about a previously underfunded topic and deepen understanding within the hearing research field, he said. Allen Ryan, Ph.D., another member of the CST, added the program is “immensely valuable for helping young scientists advance to receive a Research Project Grant [R01] from the National Institutes of Health.” Every dollar invested in ERG grantees yields $91 from the NIH.

The HRP consortium also convened at ARO to deliver updates on five active projects following their most recent Seattle meeting. Bioinformatics and epigenetics were major focal points with Ronna Hertzano, M.D., Ph.D., showcasing updates to the gEAR database that she created (“Gene Expression Analysis Resource”) and Neil Segil, Ph.D., reporting on gene changes in the mouse inner ear, a project he works on with fellow HRP scientists Michael Lovett, Ph.D., David Raible, Ph.D., and Jennifer Stone, Ph.D.

Stefan Heller, Ph.D., who spoke about his Stanford lab’s work on transcriptome changes in single chick cells, noted: "The investments in the Hearing Restoration Project are truly paying off, especially in the last one to two years. We have had major papers published and obtained National Institutes of Health support with the help of funding for the HRP consortium. It has given us the chance to focus on getting the highest possible quality of data—in my mind, the most important foundation for future work."

HHF looks forward to work to come from Ngodup, Anderson, McCullagh, and other ERG grantees, as well as the collaborative efforts of the HRP to advance a biological cure for hearing loss. We sincerely thank our generous donors and supporters who make this life-changing work possible.

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New Insights into the Development of the Hair Cell Bundle

By Yishane Lee

Recent genetic studies have identified that the protein Ripor2 (formerly known as Fam65b) is an important molecule for hearing. It localizes to the stereocilia of auditory hair cells and causes deafness when mutations disrupt its function.

In a study published in the Journal of Molecular Medicine in November 2018, Oscar Diaz-Horta, Ph.D., a 2017 Emerging Research Grants (ERG) scientist, and colleagues further show the role the protein plays by demonstrating how it interacts with other proteins during the development of the hair cell bundle. The team found that the absence of Ripor2 changes the orientation of the hair cell bundle, which in turn affects hearing ability.

Ripor2 interacts with Myh9, a protein encoded by a known deafness gene, and Myh9 is expressed in the hair cell bundle stereocilia as well as its kinocilia (apices). The team found that the absence of Ripor2 means that Myh9 is low in abundance. In the study, Ripor2-deficient mice developed hair cell bundles with atypically localized kinocilia and reduced abundance of a phosphorylated form of Myh9. (Phosphorylation is a cellular process critical for protein function.)

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Another specific kinociliary protein, acetylated alpha tubulin, helps stabilize cell structures. The researchers found it is also reduced in the absence of Ripor2.

The study concludes that Ripor2 deficiency affects the abundance and/or role of proteins in stereocilia and kinocilia, which negatively affects the structure and function of the auditory hair cell bundle. These newly detailed molecular aspects of hearing will help to better understand how, when these molecular actions are disrupted, hearing loss occurs.

A 2017 ERG scientist funded by the Children’s Hearing Institute (CHI), Oscar Diaz-Horta, Ph.D., was an assistant scientist in the department of human genetics at the University of Miami. He passed away suddenly in August 2018, while this paper was in production. HHF and CHI both send our deepest condolences to Diaz-Horta’s family and colleagues.

We need your help supporting innovative hearing and balance science through our Emerging Research Grants program. Please make a contribution today.

 
 
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Headlines in Hearing Restoration

By Yishane Lee

The cornerstone of Hearing Health Foundation for six decades has been funding early-career hearing and balance researchers through its Emerging Research Grants (ERG) program. Many ERG scientists have gone on to obtain prestigious National Institutes of Health (NIH) funding to continue their HHF-funded research; since 1958, each dollar awarded to ERG scientists by HHF has been matched by NIH investments of more than $90. Within the scientific community, ERG is a competitive grant awarded to the most promising investigators, and we’re always especially pleased when our ERG alumni who are now also members of or affiliated with our Hearing Restoration Project consortium make headlines in the mainstream news for their scientific breakthroughs.

Hair cells in the mouse cochlea courtesy of the lab of Hearing Restoration Project (HRP) member Andy Groves, Ph.D., Baylor College of Medicine.

Hair cells in the mouse cochlea courtesy of the lab of Hearing Restoration Project (HRP) member Andy Groves, Ph.D., Baylor College of Medicine.

Ronna Hertzano, M.D., Ph.D. (2009–10): Hearing Restoration Project consortium member Hertzano, an associate professor at the University of Maryland School of Medicine, and colleagues identified a gene, Ikzf2, that acts as a key regulator for outer hair cells whose loss is a major cause of age-related hearing loss. The Ikzf2 gene encodes helios, a transcription factor (a protein that controls the expression of other genes). The mutation of the gene in mice impairs the activity of helios in the mice, leading to an outer hair cell deficit.

Reporting in the Nov. 21, 2018, issue of Nature, the team tested whether the opposite effect could be created—if an abundance of helios could boost the population of outer hair cells. They introduced a virus engineered to overexpress helios into the inner ear hair cells of newborn mice, and found that some mature inner hair cells became more like outer hair cells by exhibiting electromotility, a property limited to outer hair cells. The finding that helios can drive inner hair cells to adopt critical outer hair cell characteristics holds promise for future treatments of age-related hearing loss.

Patricia White, Ph.D. (2009, 2011), with Hearing Restoration Project member Albert Edge, Ph.D.: White, a research associate professor at the University of Rochester Medical Center, Edge, a professor of otolaryngology at Massachusetts Eye and Ear and Harvard Medical School, and team have been able to regrow the sensory hair cells found in the mouse cochlea. The study, published in the European Journal of Neuroscience on Sep. 30, 2018, builds on White’s prior research that identified a family of receptors called epidermal growth factor (EGF) that is responsible for activating supporting cells in the auditory organs of birds. When triggered, these cells proliferate and foster the generation of new sensory hair cells. In mice, EGF receptors are expressed but do not drive regeneration of hair cells, so it could be that as mammals evolved, the signaling pathway was altered.

The new study aimed to unblock the regeneration of hair cells and also integrate them with nerve cells, so they are functional, by switching the EGF signaling pathway to act as it does in birds. The team focused on a specific receptor called ERBB2, found in supporting cells. They used a number of methods to activate the EGF signaling pathway: a virus targeting ERBB2 receptors; mice genetically altered to overexpress activated ERBB2; and two drugs developed to stimulate stem cell activity in the eye and pancreas that are already known to activate ERBB2 signaling. The researchers found that activating the ERBB2 pathway triggered a cascading series of cellular events: Supporting cells began to proliferate and started the process of activating other neighboring stem cells to lead to “apparent supernumerary hair cell formation,” and these hair cells’ integration with the network of neurons was also supported.

This was prepared using press materials from the University of Maryland and the University of Rochester. For more, see hhf.org/hrp.

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The People Behind the Science

By Yishane Lee

Eight years ago we introduced a column called “Meet the Researcher.” Placed on the last page of the magazine (prime editorial real estate!), the MTR column was designed as a way to give our Emerging Research Grants (ERG) scientists a place to talk about their ERG project in more detail—and in lay terms for our readers—including its genesis, planned execution, and future goals.

Credit: Jane G. Photography

Credit: Jane G. Photography

“Meet the Researcher” also is an opportunity for us to glimpse the person behind the science, with the researchers sharing how they became interested in their field and whether they have any personal connection to hearing conditions. Perhaps not surprisingly, many researchers do become interested in hearing and balance science as a result of their own experience with hearing loss. For instance, 2010 ERG scientist Judith Kempfle, M.D., told us she received an artificial eardrum at age 13, after many ear infections that her brother also got when they were kids growing up in Germany. With her ERG funded by the Royal Arch Masons General Grand Chapter International, Kempfle has gone on to work on many papers with Hearing Restoration Project member Albert Edge, Ph.D. (including a recent one about the effort to deliver drugs directly to the inner ear).

Ed Bartlett, Ph.D., Purdue University

Ed Bartlett, Ph.D., Purdue University

Also a Royal Arch Masons grantee, 2011 ERG scientist Ed Bartlett, Ph.D., who published research on the lasting effects of blast shock waves on auditory processing, remembers asking his teacher whether we actually hear thoughts or if it something else. “So, I guess I was destined for auditory neuroscience,” says Bartlett, who also earned ERG funding in 2003, 2004, and 2009.

2011 and 2012 ERG scientist Regie Santos-Cortez, M.D., Ph.D., who earned the Collette Ramsey Baker Award named after HHF’s founder, spoke about the challenges of getting access to genetic information for her study that eventually pinpointed a gene mutation linked to a predisposition for ear infections. 2012 ERG scientist Bradley J. Walters, Ph.D., says he started out studying evolutionary biology, switched to studying regenerating damaged brain tissue, and then switched to hearing research. “I realized a lot of the ideas I had been working on in the brain could be applied to the ear,” he says. A 2017 paper he coauthored described successfully using gene therapy to regenerate hair cells in adult mice.

Alan Kan, Ph.D., University of Wisconsin, Madison

Alan Kan, Ph.D., University of Wisconsin, Madison

An early love of logic puzzles for 2013 ERG scientist Alan Kan, Ph.D., a Royal Arch Masons grantee, turned into studying audio engineering and his 2018 paper looking at how to improve speech understanding among people who use bilateral cochlear implants. Fellow 2013 Royal Arch Masons recipient Ross Maddox, Ph.D., remembers varying how he cupped his hands over his ears to get different sounds, leading to an interest in auditory processes and, eventually, research on how auditory and visual input is synthesized to understand sound.

After 26 years as a clinical audiologist, Royal Arch Masons 2014 ERG scientist Samira Anderson, Ph.D., switched to research. “Part of my motivation came from working with patients who struggled with their hearing aids,” she says. “I was frustrated that I was unable to predict who would benefit from hearing aids based on the results of audiological evaluations.” She produced three papers on the topic, bringing us closer to improving fit for and increasing the use of hearing aids.

Likewise, fellow Royal Arch Masons grantee Srikanta Mishra, Ph.D., produced two papers, one in 2017 and one in 2018, on children’s hearing that stemmed from his 2014 ERG grant—work that also led to a prestigious National Institutes on Deafness and Other Communication Disorders grant. And we liked the backstory for 2014 ERG scientist Brad Buran, Ph.D., so much that we put him on the cover of our magazine. Buran, who wears cochlear implants, multitasks during happy hour with his colleagues. “In an environment where it’s hard to hear,” he says, “within an hour they have all the information they need to use Cued Speech,” which uses visual representations of phonemes.

Beula Magimairaj, Ph.D., University of Central Arkansas

Beula Magimairaj, Ph.D., University of Central Arkansas

In 2015, we expanded our coverage of ERG recipients, so that every grantee is profiled in a “Meet the Researcher” column, all available online. Three papers resulted from the Royal Arch Masons grant received by 2015 ERG scientist Beula Magimairaj, Ph.D., and her research into children’s speech perception in noise and auditory processing (the third paper is in press). Funded by Hyperacusis Research Ltd., 2015 ERG scientist Kelly Radziwon, Ph.D., has managed to create a reliable animal model for loudness hyperacusis (essentially, inducing loudness intolerance in a rat and making sure it reacts to gradually increasing sound intensities) as well as finding a potential link between neuroinflammation and hyperacusis. 2015 and 2016 ERG scientist Wafaa Kaf, Ph.D.—who has 18 other family members (and counting!) who work in science—has been investigating Ménière’s disease, publishing on improving its diagnosis as it can be mistaken for other conditions, and the use of electrocochleography (ECochG) for diagnosing and monitoring the hearing and balance disorder.

Elizabeth McCullagh, Ph.D., University of Colorado

Elizabeth McCullagh, Ph.D., University of Colorado

A karaoke fan who admits he “cannot resist Celine Dion,” Royal Arch Masons 2016 ERG scientist Richard Felix II, Ph.D. published on the greater-than-expected role of lower-level brain regions on speech processing. Fellow Royal Arch Masons grantee, 2016 ERG scientist Elizabeth McCullagh, Ph.D., makes her own cheese and beer in between uncovering new clues to sound localization problems in the genetic condition known as Fragile X syndrome, which can lead to autism.

Rahul Mittal, Ph.D., University of Miami Miller School of Medicine

Rahul Mittal, Ph.D., University of Miami Miller School of Medicine

2016 ERG scientist Harrison Lin, Ph.D., funded by The Barbara Epstein Foundation Inc., credits his older brother, also an otolaryngologist, for developing in him a love for science. He coauthored a January 2018 JAMA Otolaryngology–Head & Neck Surgery paper that detailed the gap between hearing loss diagnoses and treatments. 2016 ERG scientist Rahul Mital, Ph.D., who says he’d write fiction if not doing research, published an overview of hair cell regeneration, and Julia Campbell, Au.D., Ph.D., whose 2016 grant was funded by the Les Paul Foundation, understands firsthand what is feels like to have tinnitus, a topic she recently published a paper that investigated mild tinnitus in young patients with typical hearing. Hyperacusis Research-funded 2016 ERG scientist Xiying Guan, Ph.D., whose parents grew up doing manual labor in China, published a paper evaluating a treatment for conductive hyperacusis.

Some of our 2017 ERG scientists are already publishing. Royal Arch Masons grantee Inyong Choi, Ph.D., produced research on hybrid cochlear implants, which make use of residual hearing to produce more natural hearing. Oscar Diaz-Horta, Ph.D., whose 2017 ERG grant was funded by the Children’s Hearing Institute, investigated hair cell bundle structure and orientation. Very regretfully, Diaz-Horta died unexpectedly just as this paper was published.

Ian Swinburne, Ph.D., Harvard Medical School

Ian Swinburne, Ph.D., Harvard Medical School

Ian Swinburne, Ph.D., one of our Ménière’s Disease Grants scientists during its inaugural year in 2017, published a paper detailing one possible cause of Ménière’s disease. Swinburne and team discovered a structure in the inner ear’s endolymphatic sac acts a pressure-sensitive relief valve. Its failure may account for problems with inner ear fluid pressure and volume that may lead to hearing and balance disorders, including Ménière’s. “One activity I loved as a child was waterworks: building canals and aqueducts out of sand or dirt and then pouring water through them just to watch it flow,” he says. “Now I recognize an echo of that play in my study of water pressure and flow within the ear.”

We very much look forward to published research from all of our ERG scientists, including our latest crop of 2018 ERG scientists, whose ranks include a former college mascot, a violinist, a horse rider (of a horse named Gandalf), a Tibetan neuroscientist (and cookbook writer), a cricket player, a nonprofit cook who has prepared meals for 50,000 people, a dancer (including in flash mobs), and a builder of airplane scale models. Our ERG scientists deliver surprises of all sorts, from their backgrounds and how they got to where they are to the ground-breaking science they are spearheading in the lab.

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Accomplishments by ERG Alumni

By Elizabeth Crofts

Progress Investigating Potential Causes and Treatments of Ménière’s Disease

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Gail Ishiyama, M.D., a clinician-scientist who is a neurology associate professor at UCLA’s David Geffen School of Medicine, has been investigating balance disorders for nearly two decades and recently coauthored two studies on the topic. While not directly funded by HHF, Ishiyama is a 2016 Emerging Research Grants recipient and also received a Ménière’s Disease Grant in 2017.

Ishiyama and colleague’s December 2018 paper in the journal Brain Research investigated oxidative stress, which plays a large role in several inner ear diseases as well as in aging. Oxidative stress is an imbalance between the production of free radicals and antioxidant defenses. The gene responsible for reducing oxidative stress throughout the body is called nuclear factor (erythroid-derived 2)-like 2, or NRF2. Ishiyama’s study looked at the localization of NRF2 in the proteins in the cells of the human cochlea and vestibule. It was found that NRF2-immunoreactivity (IR) was localized in the organ of Corti of the cochlea. Additionally, it was observed that NRF2-IR decreases significantly in the cochlea of older individuals. The team postulates for future studies that modulation of NRF2 expression may protect from hearing loss that results from exposure to noise and ototoxic drugs.

In a January 2018 report in the journal Otology & Neurotology, Ishiyama and team researched endolymphatic hydrops (EH), a ballooning of the endolymphatic fluid system in the inner ear that is associated with Ménière’s disease. Symptoms include fluctuating hearing loss, as well as vertigo, tinnitus, and pressure in the ear.

For the study, patients with EH and vestibular schwannoma were tested to evaluate the clinical outcome of patients when EH is treated medically. Vestibular schwannoma, also known as acoustic neuroma, are benign tumors that grow in the vestibular system of the inner ear, which controls balance. Often when patients develop episodic vertigo spells and have a known diagnosis of vestibular schwannoma, surgeons recommend surgical intervention, as they attribute the symptoms to the vestibular schwannoma. However, a noninvasive treatment may hold promise. Through the use of high-resolution MRI scans, the researchers found that when EH coexists with vestibular schwannoma in a patient, and the patient also experiences vertigo spells, a medical treatment for EH—that is, the use of diuretics to relieve inner ear fluid buildup—may alleviate the vestibular symptoms.

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A 2016 ERG scientist funded by The Estate of Howard F. Schum, Gail Ishiyama, M.D., is an associate professor of neurology at UCLA’s David Geffen School of Medicine. She also received a 2017 Ménière’s Disease Grant.


New Insights Into Aging Effects on Speech Recognition

Age-related changes in perceptual organization have received less attention than other potential sources of decline in hearing ability. Perceptual organization is the process by which the auditory system interprets acoustic input from multiple sources, and creates an auditory scene. In daily life this is essential, because speech communication occurs in environments in which background sounds fluctuate and can mask the intended message.

Perceptual organization includes three interrelated auditory processes: glimpsing, speech segregation, and phonemic restoration. Glimpsing is the process of identifying recognizable fragments of speech and connecting them across gaps to create a coherent stream. Speech segregation refers to the process where the glimpses (speech fragments) are separated from background speech, to focus on a single target when the background includes multiple talkers. Phonemic restoration refers to the process of filling in missing information using prior knowledge of language, conversational context, and acoustic cues.

A July 2018 study in The Journal of the Acoustical Society of America by William J. Bologna, Au.D., Ph.D., Kenneth I. Vaden, Jr., Ph.D., Jayne B. Ahlstrom, M.S., and Judy R. Dubno, Ph.D., investigated these three components of perceptual organization to determine the extent to which their declines may be the source of increased difficulty in speech recognition with age. Younger and older adults with typical hearing listened to sentences interrupted with either silence or envelope-modulated noise, presented in quiet or with a competing talker.

As expected, older adults performed more poorly than younger adults across all speech conditions. The interaction between age and the duration of glimpses indicated that, compared with younger adults, older adults were less able to make efficient use of limited speech information to recognize keywords. There was an apparent decline in glimpsing, where interruptions in speech had a larger effect on the older adult group.

Older adults saw a greater improvement in speech recognition when envelope modulations were partially restored, leading to better continuity. This demonstrated that with age comes a poorer ability to resolve temporal distortions in the envelope. In speech segregation, the decline in performance with a competing talker was expected to be greater for older adults than younger adults, but this was not supported by the data.

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A 2015 Emerging Research Grants scientist, Kenneth I. Vaden, Jr., Ph.D., is a research assistant professor in the department of otolaryngology–head and neck surgery at the Medical University of South Carolina.

A 1986–88 ERG scientist, Judy R. Dubno, Ph.D., is a member of HHF’s Board of Directors. The study’s lead author, William Bologna, Au.D., Ph.D., is a postdoctoral research fellow at the National Center for Rehabilitative Auditory Research in Portland, Oregon.

A 2018 HHF intern, Author Elizabeth Crofts is a junior at Boston University studying biomedical engineering. For our continually updated list of published papers by ERG alumni, see hhf.org/erg-alumni.

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ERG Grantees' Advancements in OAE Hearing Tests, Speech-in-Noise Listening

By Yishane Lee and Inyong Choi, Ph.D.

Support for a Theory Explaining Otoacoustic Emissions: Fangyi Chen, Ph.D.

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It’s a remarkable feature of the ear that it not only hears sound but also generates it. These sounds, called otoacoustic emissions (OAEs), were discovered in 1978. Thanks in part to ERG research in outer hair cell motility, measuring OAEs has become a common, noninvasive hearing test, especially among infants too young to respond to sound prompts..

There are two theories about how the ear produces its own sound emanating from the interior of the cochlea out toward its base. The traditional one is the backward traveling wave theory, in which sound emissions travel slowly as a transverse wave along the basilar membrane, which divides the cochlea into two fluid-filled cavities. In a transverse wave, the wave particles move perpendicular to the wave direction. But this theory does not explain some anomalies, leading to a second hypothesis: The fast compression wave theory holds that the emissions travel as a longitudinal wave via lymph fluids around the basilar membrane. In a longitudinal wave, the wave particles travel in the same direction as the wave motion.

Figuring out how the emissions are created will promote greater accuracy of the OAE hearing test and a better understanding of cochlear mechanics. Fangyi Chen, Ph.D., a 2010 Emerging Research Grants (ERG) recipient, started investigating the issue at Oregon Health & Science University and is now at China’s Southern University of Science and Technology. His team’s paper, published in the journal Neural Plasticity in July 2018, for the first time experimentally validates the backward traveling wave theory.

Chen and his coauthors—including Allyn Hubbard, Ph.D., and Alfred Nuttall, Ph.D., who are each 1989–90 ERG recipients—directly measured the basilar membrane vibration in order to determine the wave propagation mechanism of the emissions. The team stimulated the membrane at a specific location, allowing for the vibration source that initiates the backward wave to be pinpointed. Then the resulting vibrations along the membrane were measured at multiple locations in vivo (in guinea pigs), showing a consistent lag as distance increased from the vibration source. The researchers also measured the waves at speeds in the order of tens of meters per second, much slower than would be the speed of a compression wave in water. The results were confirmed using a computer simulation. In addition to the wave propagation study, a mathematical model of the cochlea based on an acoustic electrical analogy was created and simulated. This was used to interpret why no peak frequency-to-place map was observed in the backward traveling wave, explaining some of the previous anomalies associated with this OAE theory.

Speech-in-Noise Understanding Relies on How Well You Combine Information Across Multiple Frequencies: Inyong Choi, Ph.D.

Understanding speech in noisy environments is a crucial ability for communications, although many individuals with or without hearing loss suffer from dysfunctions in that ability. Our study in Hearing Research, published in September 2018, finds that how well you combine information across multiple frequencies, tested by a pitch-fusion task in "hybrid" cochlear implant users who receive both low-frequency acoustic and high-frequency electric stimulation within the same ear, is a critical factor for good speech-in-noise understanding.

In the pitch-fusion task, subjects heard either a tone consisting of many frequencies in a simple mathematical relationship or a tone with more irregular spacing between frequencies. Subjects had to say whether the tone sounded "natural" or "unnatural" to them, given the fact that a tone consisting of frequencies in a simple mathematical relationship sounds much more natural to us. My team and I are now studying how we can improve the sensitivity to this "naturalness" in listeners with hearing loss, expecting to provide individualized therapeutic options to address the difficulties in speech-in-noise understanding.

2017 ERG recipient Inyong Choi, Ph.D., is an assistant professor in the department of communication sciences and disorders at the University of Iowa in Iowa City.

We need your help supporting innovative hearing and balance science through our Emerging Research Grants program. Please make a contribution today.

 
 
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HHF 2019 Grant Applications Open

By Lauren McGrath

We are excited to inform you that the applications for Hearing Health Foundation (HHF)'s 2019 Emerging Research Grants (ERG) and Ménière's Disease Grants (MRG) programs are officially open as of September 1.

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HHF's ERG grants provide seed money to stimulate data collection that leads to a continuing, independently fundable line of research. According to a 2017 analysis, every $1 of funding that HHF awards to ERG grantees is matched by the NIH with $91.

ERG grant funding shall not exceed $30,000 for the one-year project period, and only research proposals in the following topic will be considered for the 2019 ERG cycle: General Hearing Health (GHH)*,  [Central] Auditory Processing Disorders, Hearing Loss in Children, Hyperacusis, Ménière’s Disease, Ototoxic Medications, Tinnitus, and Usher Syndrome.

More Information About ERG
Begin Your ERG Application

The highly competitive Ménière’s Disease Grants (MDG) program funds scientists to better our understanding of this complicated condition with an eye for better treatments and cures for those who suffer from Ménière’s disease.

MDG grant funding shall not exceed $125,000 for the two-year project period. Areas of interest for the 2019 MDG Cycle include: the mechanisms of endolymphatic hydrops; genetics of Ménière’s disease; development and validation of biomarkers, including imaging and/or electrophysiologic and behavioral measures for its diagnosis and measurement of therapeutic effectiveness; animal models of Ménière’s disease; and the development of novel therapeutics.

More Information About MDG
Begin Your MDG Application

Applications for both ERG and MDG will close Tuesday, January 15.

If you have any questions about the grant program and processes, contact us at grants@hhf.org.  
Please forward and share this information with your colleagues who may be interested.

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Understanding Individual Variances in Hearing Aid Outcomes in Quiet and Noisy Environments

By Elizabeth Crofts

Evelyn Davies-Venn, Au.D., Ph.D.

Evelyn Davies-Venn, Au.D., Ph.D.

More than 460 million people worldwide live with some form of hearing loss. For most, hearing aids are the primary rehabilitation tool, yet there is no one-size-fits-all approach. As a result, many hearing aid users are frustrated by their listening experiences, especially understanding speech in noise.

Evelyn Davies-Venn, Au.D., Ph.D., of the University of Minnesota is currently focusing on two projects, one of which is funded by Hearing Health Foundation (HHF) through its Emerging Research Grants (ERG) program, that will enhance the customization of hearing aids. She presented the two projects at the Hearing Loss Association of America (HLAA) convention in June.

Davies-Venn explains that some of the factors dictating individual variance in hearing aid listening outcomes in noisy environments include audibility, spectral resolution, and cognitive ability. Audibility changes—how much of the speech spectrum is available to the hearing aid user—is the biggest factor. “Speech must be audible before it is intelligible,” Davies-Venn says. Another primary factor is spectral resolution, or your ear’s ability to make use of the spectrum or frequency changes in sounds. This also directly affects listening outcomes.

Secondary factors include the user’s working memory and the volume of the amplified speech. These impact how well someone can handle making sense of distortions (from ambient noise as well as from signal processing) in an incoming speech signal. Working memory is needed to provide context in the event of missing speech fragments, for instance. Needless to say, it is a challenge for conventional hearing aid technology to address all of these complex variables.

Davies-Venn’s highlights two emerging projects that take an innovative approach to resolving this challenge. The first project aims to improve hearing aid success focuses on an emerging technology called the “cognitive control of a hearing aid,” or COCOHA. It is an improved hearing aid that will analyze multiple sounds, complete an acoustic scene analysis, and separate the sounds into individual streams, she says.

Then, based on the cognitive/electrophysiological recordings from the individual, the COCOHA will select the specific stream that the person is interested in listening to and amplify it—such as a particular speaker’s voice. The cognitive recording is captured with a noninvasive, far-field measure of electrical signals emitted from the brain in response to sound stimuli (similar to how an electroencephalogram, EEG, captures signals).

Davies-Venn’s ERG grant from HHF will support research on the use of electrophysiology, far-field or distant (i.e. recorded at the scalp) electrical signals from the brain, to design hearing aid algorithms that can control individual variances due to level-induced (i.e. high intensity) distortions from hearing aids.

The other project involves sensory substitution. This project explores the conversion of speech to another sense—for example, touch—through a mobile processing device or a “skin hearing aid.” For the device to function, a vibration is relayed to the brain for speech understanding. This technology seems cutting edge, but is believed to have been invented in the 1960s by Paul Bach-y-Rita, M.D., of the Smith-Kettlewell Institute of Visual Sciences in San Francisco. Even though it has not yet been incorporated into hearing aid technology intended for mass production, David Eagleman, Ph.D., of Stanford University and others are hoping to make this a reality.

Davies-Venn’s research motives are inspired by a personal connection to her work. “I have a conductive hearing loss myself,” she says. “I had persistent/chronic ear infections as a child that left me a bit delayed in developing speech, and still get ear infections as an adult and have ground accustomed to the low-frequency hearing loss that results until they resolve.” She also has family members with hearing loss and understands the importance of developing more advanced hearing assistance technology.

The projects are in the early stages, and it may take as long as a decade for them to reach the market from the concept. “The goal is to develop individualized hearing aid signal processing to improve treatment outcomes in noisy soundscapes,” Davies-Venn says. “We want to say, this is the most optimal treatment protocol, and it’s different from this person’s, even though you have the same hearing threshold.” Solving hearing aid variances in a precise, individual manner that accounts for variables such as age and cognitive ability will improve communication and quality of life for the millions with hearing loss who use hearing technology.

We need your help supporting innovative hearing and balance science through our Emerging Research Grants program. Please make a contribution today.

 
 
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Hearing Loss Film “Hearing Hope” Captures Personal Strength, Scientific Vision

Hearing Health Foundation (HHF) has created a new short film, “Hearing Hope,” to expand awareness of hearing health through the voices of those who benefit from and those who carry out the foundation’s life-changing work.

"It took me longer to talk than most kids. Because I couldn't understand what they were saying so I couldn't copy it," explains Emmy, 7.

"It took me longer to talk than most kids. Because I couldn't understand what they were saying so I couldn't copy it," explains Emmy, 7.

The third most prevalent chronic physical condition in the U.S., hearing loss can affect anyone—from first-grader Emmy to retired U.S. Army Colonel John—but its reach is often underestimated. “It’s one of the most common sensory deficits in humans,” explains cochlear implant surgeon Dr. Anil Lalwani. “I think we have to go from it being hidden to being visible.”

Both a hearing aid user and cochlear implant recipient, seventh-grader Alex is doing his part to make hearing loss less hidden. Smiling, he says he wants people to know that hearing with his devices makes him happy. John wishes to be an advocate for veterans and all who live with hearing loss and tinnitus.

When she received her hearing loss diagnosis at 17, NASA engineer Renee never thought she'd be living her dream.

When she received her hearing loss diagnosis at 17, NASA engineer Renee never thought she'd be living her dream.

The film also highlights resilience in response to the challenges associated with hearing conditions. Video participant Renee saw her dream of becoming an astronaut halted at 17 when her hearing loss was detected. Now she helps send people to space as an engineer at NASA.

Sophia describes the “low, low rock bottom” she hit when she was diagnosed with Usher Syndrome, the leading cause of deafblindness. Yet she feels special knowing her disability shapes her and sets her apart.

Jason recounts having no resources for hearing loss in children when his son, Ethan, failed his newborn hearing screening. Today he’s grateful for Ethan’s aptitude for language, made possible through his early hearing loss intervention.

With the support of HHF, more progress is made each year. “I’m glad that the doctors are trying to figure out how fish and birds can restore their hearing,” says Emmy.

For the past 60 years, HHF has funded promising hearing science and in 2011 established the Hearing Restoration Project (HRP), an international consortium dedicated to finding biological cures for hearing loss using fish, bird, and mouse models to replicate the phenomenon of hearing loss reversal in humans.

“If [the HRP] can achieve that goal of hearing restoration...that would be a marvelous thing for hearing loss,” reiterates Dr. Robert Dobie.

Through “Hearing Hope,” HHF would like to share its mission and message of hope to as many individuals as possible and reassure those with hearing loss and their loved ones they are not alone. As an organization that channels all efforts into research and education, HHF would greatly appreciate any assistance or suggestions to increase visibility of the film.

Watch the full film at www.hhf.org/video. Closed captioning is available.

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Understanding a Pressure Relief Valve in the Inner Ear

By Ian Swinburne, Ph.D.

The inner ear senses sound to order to hear as well as sensing head movements in order to balance. Sounds or body movements create waves in the fluid within the ear. Specialized cells called hair cells, because of their thin hairlike projections, are submerged within this fluid. Hair cells bend in response to these waves, with channels that open in response to the bending. The makeup of the ear’s internal fluid is critical because as it flows through these channels its contents encode the information that becomes a biochemical and then a neural signal. The endolymphatic sac of the inner ear is thought to have important roles in stabilizing this fluid that is necessary for sensing sound and balance.

This study helps unravel how a valve in the inner ear's endolymphatic sac acts to relieve fluid pressure, one key to understanding disorders affected by pressure abnormalities such as Ménière’s disease.

This study helps unravel how a valve in the inner ear's endolymphatic sac acts to relieve fluid pressure, one key to understanding disorders affected by pressure abnormalities such as Ménière’s disease.

While imaging transparent zebrafish, my team and I found a pressure-sensitive relief valve in the endolymphatic sac that periodically opens to release excess fluid, thus preventing the tearing of tissue. In our paper published in the journal eLife June 19, 2018, we describe how the relief valve is composed of physical barriers that open in response to pressure. The barriers consist of cells adhering to one another and thin overlapping cell projections that are continuously remodeling and periodically separating in response to pressure.

The unexpected discovery of a physical relief valve in the ear emphasizes the need for further study into how organs control fluid pressure, volume, flow, and ion homeostasis (balance of ions) in development and disease. It suggests a new mechanism underlying several hearing and balance disorders characterized by pressure abnormalities, including Ménière’s disease.

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Here is a time-lapse video of the endolymphatic sac, with the sac labeled “pressure relief valve” at 0:40.

2017 Ménière’s Disease Grants scientist Ian A. Swinburne, Ph.D., is conducting research at Harvard Medical School. He was also a 2013 Emerging Research Grants recipient.

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