How Noise Affects the Palate

By Melissa Osgood, Cornell University

If you're planning to fly over the holiday, plan to drink some tomato juice. While examining how airplane noise affects the palate, Cornell University food scientists found sweetness suppressed and a tasty, tender tomato surprise: umami.

A Japanese scientific term, umami describes the sweet, savory taste of amino acids such as glutamate in foods like tomato juice, and according to the new study, in noisy situations -- like the 85 decibels aboard a jetliner -- umami-rich foods become your taste bud's best buds.

"Our study confirmed that in an environment of loud noise, our sense of taste is compromised. Interestingly, this was specific to sweet and umami tastes, with sweet taste inhibited and umami taste significantly enhanced," said Robin Dando, assistant professor of food science. "The multisensory properties of the environment where we consume our food can alter our perception of the foods we eat."

With Dando, Kimberly Yan, co-authored the study, "A Crossmodal Role for Audition in Taste Perception," published online in March in the Journal of Experimental Psychology: Human Perception and Performance. The research will appear in a forthcoming print edition of the journal.

The study may guide reconfiguration of airline food menus to make airline food taste better. Auditory conditions in air travel actually may enhance umami, the researchers found. In contrast, exposure to the loud noise condition dulled sweet taste ratings.

Airlines acknowledge the phenomenon. German airline Lufthansa had noticed that passengers were consuming as much tomato juice as beer. The airline commissioned a private study released last fall that showed cabin pressure enhanced tomato juice taste.

Taste perception depends not only on the integration of several sensory inputs associated with the food or drink itself, but also on the sensory attributes of the environment in which the food is consumed, the scientists say.

"The multisensory nature of what we consider 'flavor' is undoubtedly underpinned by complex central and peripheral interactions," said Dando. "Our results characterize a novel sensory interaction, with intriguing implications for the effect of the environment in which we consume food."

The above post is reprinted from materials provided by Cornell University.

How Hearing Loss and Tinnitus Affect Our Veterans

By Emily Shepard

Today is Veterans Day. The holiday is important not only because it honors our soldiers, but also because it is a time to raise awareness about their experiences on and off the battlefield. Hearing loss is a major health issue for soldiers, both active duty personnel and veterans. Any form of hearing loss can be detrimental to soldiers on duty, as the ability to hear signs of danger and to communicate with fellow soldiers is crucial for mission success and, more importantly, survival. According to the U.S. Department of Defense’s Hearing Center of Excellence (HCE), a whopping 60% of veterans have returned home with hearing loss or tinnitus over the last decade.

The Fall 2015 issue of Hearing Health magazine focused on hearing loss and tinnitus among U.S. military service members and veterans. In “Tuning Out the Noise,” Ashleigh Byrnes explains that tinnitus is one of the most prevalent injuries among veterans.  The number of veterans diagnosed with service-connected tinnitus is estimated at 1.5 million. According to Byrnes, persistent tinnitus can be “described as noise that prevents sleep or the ability to concentrate” and may “leave patients more vulnerable to other mental health problems, such as depression and anxiety.” Luckily, there are treatment methods, new and old, that can ease the symptoms of tinnitus. 

Sound therapy, long regarded as one of the most successful ways to treat tinnitus, has been practiced for more than 30 years. Between 60-90% of patients report relief from their symptoms using this method. Another option is cognitive behavioral therapy (CBT), which may include the use of relaxation or distraction techniques, or altering the way patients think about their symptoms. Those who try sound therapy or CBT may be able to cope with tinnitus with more positive outcomes.

When it comes to hearing loss, soldiers are at an increased risk. They are susceptible to noise-induced hearing loss (NIHL) due to exposure to loud machinery and explosions on a constant basis. In combat, soldiers are often exposed to sudden noises, such as from an improvised explosive device (IED) or other similar weapons, which are difficult to predict and prevent against.  These sudden noises can result in temporary hearing loss and put military personnel at risk. However, the word “temporary” should be approached with caution. Repeated short-term hearing loss can damage the sensitive hair cells in the inner ear, causing hearing loss that becomes permanent.

With an inability to grow back, inner ear hair cells, when they are damaged or die, can lead to permanent hearing loss. HHF is actively working to reverse this trend. Researchers funded by HHF’s Emerging Research Grants program (ERG) discovered that birds have the ability to spontaneously re-grow inner ear hair cells after they are damaged and restore their hearing—unlike mammals. Through HHF’s Hearing Restoration Project (HRP), a consortium of top hearing scientists is working to translate this finding to the human ear. The HRP’s goal is to regenerate inner ear hair cells in humans and permanently restore hearing to those affected by hearing loss, such as soldiers and veterans. The HRP researchers have made significant strides in this research and have been working hard to find meaningful answers, which you can read about here.

To learn more about hearing loss and tinnitus, please visit our Veterans’ Resource Page.

Your support helps us continue this extraordinary research.

Celebrate Veterans Day and honor our troops by donating today.

Handicapable

By Kate Yandell

Dominic Pisano hadn’t even arrived on campus to start his freshman year at Johns Hopkins University when he got his first email from biomedical engineer Tilak Ratnanather. He had heard Pisano was deaf and wanted to meet with him. Ratnanather, who has been deaf since birth, showed up for the meeting accompanied by a second deaf student who would later become a doctor. “He was, like: ‘Here’s my deaf army,’” Pisano recalls.

Soon, Pisano, a soccer enthusiast from Ohio, was interpreting magnetic resonance imaging (MRI) in Ratnanather’s department. When Pisano decided he wanted to go to medical school, Ratnanather was ready to introduce him to his wide network of friends in the otolaryngology department at Hopkins. Pisano assisted in MRI research at Hopkins for a year before attending Tufts University School of Medicine in Boston.

“I’ll be honest with you, if it weren’t for Tilak I probably wouldn’t have gone to medical school,” says Pisano, now a resident in anesthesiology at Tufts Medical Center. “I probably wouldn’t have done biomedical engineering research. Most importantly, I probably wouldn’t have the kind of network I have.”

Photo: Tilak Ratnanather

Courtesy Johns Hopkins School of Medicine

It was this kind of service that won Ratnanather the Presidential Award for Excellence in Science, Mathematics, and Engineering Mentoring this past March. Over the years, Ratnanather has lobbied for better resources for deaf attendees at conferences, organized annual dinners for deaf researchers, helped award scholarships to hearing-impaired students through the Alexander Graham Bell Association for the Deaf and Hard of Hearing (AG Bell), and mentored more than a dozen hearing-impaired students.

“He’s by nature the most gregarious and extroverted individual,” says Howard Francis, a professor of otolaryngology at Hopkins who has known Ratnanather for 23 years. “He has a sense of mission and is committed to making it possible for others to achieve what he has achieved.”

“A lot of people have a hard time understanding him [due to his deafness-related difficulties with speech],” says Pisano, “but despite that, they still enjoy his company, and they want to be connected with him.”

Ratnanather was born in 1963 in Sri Lanka with profound hearing loss of unknown origin. His family moved to London when he was 18 months old, and he grew up wearing hearing aids and attending the Mary Hare School for Deaf Children.

Ratnanather’s parents, a pediatrician and a computer systems programmer, had high hopes for their son. “My father and I would talk about mathematics and would go through some problems at home,” he says. “I had an aptitude, and then, of course, I would go to the science museum and learn about famous mathematicians.” Ratnanather enrolled at University College London, where he met mathematician Keith Stewartson, who immediately made the young undergrad comfortable about his hearing loss and the assistive technologies he needed to use in the classroom. “I knew he would make my life easy,” says Ratnanather. “I didn’t have to worry about my deafness.”

Tragically, Stewartson died suddenly at the end of Ratnanather’s first year at university. But the young student forged ahead, and after doing some reading about Stewartson’s research on fluid dynamics, Ratnanather went on to study the subject in graduate school at the University of Oxford, receiving his D.Phil. in mathematics in 1989.

Up until that point, Ratnanather had only had occasional opportunities to learn about an area near to his heart: hearing research. This changed after he attended a research symposium at the 1990 AG Bell Convention in Washington, D.C. Fascinated by the work of William Brownell, Ratnanather approached the Johns Hopkins researcher after Brownell had given a talk about outer hair cell electromotility—the process by which these sensory cells shorten or lengthen in response to electrical impulses.

When outer hair cells change shape, they transmit mechanical force to the cochlea, amplifying the ear’s sensitivity to soft sounds at specific frequencies. Forces transmitted through pressurized fluids in outer hair cells make electromotility possible, explains Brownell, who is now at Baylor College of Medicine in Houston. He needed someone who could model the dynamics of fluid within these tiny spaces. “Tilak had the computational tools to begin to study this,” Brownell says.

Ratnanather began a postdoc in Brownell’s lab in 1991. During his postdoc, he realized he could bestow upon students the confidence his mentors fostered in him. The Internet helped him reach out to other deaf people through newsgroups. Lina Reiss, who had severe hearing loss by age 2, first met Ratnanather when she was an undergraduate at Princeton University and he replied to an online post in which she introduced herself to one of these newsgroups.

The daughter of two Ph.D.s, Reiss had always known that she wanted to go into the sciences. But she was not sure what career would be possible with her hearing loss. “I didn’t have any role models of what it was like to be a deaf faculty member,” she recalls. “Until I met [Tilak and some of his deaf friends], I couldn’t imagine becoming a professor.”

Ratnanather helped get Reiss a summer internship in the hearing-research lab of a colleague at Johns Hopkins, where she studied how neurons in the brain stem encode and process sound. Enthralled with the research, she went on to do her Ph.D. in biomedical engineering in the same lab. She is now an assistant professor at Oregon Health & Science University in Portland researching how hearing loss, hearing aids, and cochlear implants influence the way people perceive sound.

Ratnanather now primarily does brain-mapping research focused on understanding how brain structures are altered in people with diseases such as schizophrenia, Alzheimer’s, and bipolar disorder. But hearing science continues to influence his work. He has published several recent studies on fluid dynamics and hair cell function and has upcoming papers on imaging the auditory regions of the brain in deaf adults and babies.

And, spurred partly by his own cochlear implant surgery in 2012, Ratnanather has created an app for adults learning how to hear following the surgery. Called Speech Banana, the app is named after the banana-shaped region in an audiogram that contains human speech.

More than just providing professional connections, Ratnanather has influenced how his former students navigate the world. Being deaf can make it scary to think outside the box or challenge opinions, Pisano says.  Ratnanather encourages his mentees to keep an open mind and engage with others—hearing and nonhearing alike. “That helped shape my mentality about life in general today,” Pisano says.

Reprinted with permission. "Handicapable" originally appeared in the October 2015 issue of The Scientist, a special issue devoted to hearing research. The article can be accessed online here. See also The Scientist’s Facebook page, where this article generated many comments.

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Hearing Health Foundation is thrilled that Tilak Ratnanather, D.Phil., received this outstanding honor and recognition from the White House for his mentoring efforts. Ratnanather was a recipient of an Emerging Research Grant (ERG) in 1993, and has continued to champion HHF and its mission to prevent and cure hearing loss and tinnitus.

Dominic Pisano, M.D., who is quoted in this article, served on HHF’s inaugural National Junior Board (now known as HHF’s New York Council) in 2012. He has written about his decision to get a cochlear implant (CI) on our website and the tips and tricks he used to succeed in medical school in our magazine, and he appeared in an HHF public service announcement.

Also quoted in the article, Lina Reiss, Ph.D., was an ERG recipient in 2012 and 2013, and went on to win funding from the National Institute on Deafness and Other Communication and Disorders. She cowrote a piece about hybrid CIs and the way they make use of residual hearing ability. HHF congratulates all for their achievements!

Hearing Loss Stigma?

By Terry Golson

Forty years ago I was a teenager with a mild hearing loss. An audiologist offered to fit me with bulky, ugly hearing aids. I said No thanks. But my loss was progressive and in my mid-twenties I finally got a hearing aid. It was a large plastic shell that filled the ear. It was uncomfortable and whistled from feedback, but it enabled me to hear. I wore it.

I wore my hair long and covered the aids. They were ugly and I didn’t want to have to talk about my disability unless I brought it up first.

My hearing worsened so that even with aids I struggled. I was constantly challenged in how to function with it. I wasn’t embarrassed by my loss, and I didn’t believe that people would think less of me because of it, but that didn’t lessen how difficult it was to live with a hearing loss. I’d tell people that I had trouble hearing, but it’s actually quite difficult for people to change how they speak. Some would project better for a word or two, but then resort back to their quiet voices. Early on in my loss I heard well enough to fill in the blanks. But, as my hearing declined, I couldn’t catch up. I’d miss half a sentence and nod in agreement, or I’d think that I understood something, but later would find out that I’d misheard. Also, like many people with hearing loss, it was easier to talk rather than to listen and so I would dominate a conversation, or would come across as rude because I missed the verbal clues as to when to enter and to end an interaction.

I was self-aware enough to recognize that this was happening. Eventually, I no longer cared if people saw my aids, in fact, I hoped that if they did they would speak more clearly. I wore my hair short, but no one noticed the aids. My hearing loss continued to worsen. I switched to behind-the-ear devices.  My ability to engage in conversation declined. Work options shrunk. I felt socially inept, visibly I came across as incompetent because of missed communication. Whatever judgements people were making about me, it was because of the behavior that the hearing loss caused, not what they saw in my ears.  I became even more open about my hearing loss. I discovered that once others understood what I was coping with, that they were generous and helpful. It wasn’t what was in my ears that caused any stigma – it was when people didn’t know that the aids were there!

No one thought less of me because of the devices I wore. This is truer now than ever before. Look around – most people have some sort of electronics attached to their heads. I now have cochlear implants. I still have short hair. People rarely notice them, but if they do, they don’t know what they are. Once, a stranger asked me about my “telephone.” I’ve had teenagers tell me that my CIs are really cool. The only people I’ve met who believe that there is a stigma to using hearing aids are the ones who wear them. A friend of mine has always hidden her disability because she worried that being open about it would impact on how people perceive her at her job. She’s a high-level manager at a world-renowned research lab. Recently a woman joined her team. At the first meeting this new hire announced that she wore hearing aids and there were times during communication that she would need help. No one blinked. These are people used to working with technology. They were interested and helpful. It took my friend aback. All of those years of struggling with her loss alone had been unnecessarily difficult.

I understand not wanting to show off one’s aids. I don’t want my hearing loss to be the first thing that one notices about me. Also, I’m vain enough to care that my CI’s are not beautiful. They’re the color of office furniture. But, there is hope. Another friend, Karen, recently upgraded her hearing aids to devices that are sleek and stylish. They are a vibrant blue to match her eyes. She says that her new aids are beautiful, and she’s right. Karen is 83 years old. Her hearing loss and her hearing aids have no stigma - not in her mind, and not to anyone around her. She’s a noted scientist and, because her devices enable her to stay in the hearing world, she continues to speak at conferences and is a mentor to many.

So let’s lay the idea of the stigma of wearing hearing aids to rest once and for all. It’s life without the aids that brings limitations. Now, if only my CIs were as pretty as Karen’s.

Terry Golson lives in a small town outside of Boston, Massachusetts. You can read about her work and her life at her website, HenCam.com. 

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Best Supporting Actors - In Your Ears?

By the University of Michigan Health System

This microscopic view of cells deep within the ear of a newborn mouse show in red and blue the supporting cells that surround the hair cells (green) that send sound signals to the brain. New research shows that the supporting cells can regenerate if damaged in the first days of life, allowing hearing to develop normally. This gives new clues for potential ways to restore hearing.

Credit: Guoqiang Wan, Univ. of Michigan

There’s a cast of characters deep inside your ears -- many kinds of tiny cells working together to allow you to hear. The lead actors, called hair cells, play the crucial role in carrying sound signals to the brain.

But new research shows that when it comes to restoring lost hearing ability, the spotlight may fall on some of the ear’s supporting actors – and their understudies.

In a new paper published online first by the Proceedings of the National Academy of Sciences, researchers from the University of Michigan Medical School, St. Jude Children’s Research Hospital and colleagues report the results of in-depth studies of these cells, fittingly called supporting cells.  

The research shows that damage to the supporting cells in the mature mouse results in the loss of hair cells and profound deafness. But the big surprise of this study was that if supporting cells are lost in the newborn mouse, the ear rapidly regenerates new supporting cells – resulting in complete preservation of hearing. This remarkable regeneration resulted from cells from an adjacent structure moving in and transforming into full-fledged supporting cells. 

It was as if a supporting actor couldn’t perform, and his young understudy stepped in suddenly to carry on the performance and support the lead actor -- with award-winning results.

The finding not only shows that deafness can result from loss of supporting cells -- it reveals a previously unknown ability to regenerate supporting cells that’s present only for a few days after birth in the mice.

If scientists can determine what’s going on inside these cells, they might be able to harness it to find new approaches to regenerating auditory cells and restoring hearing in humans of all ages.

Senior author and U-M Kresge Hearing Research Institute director Gabriel Corfas, Ph.D., says the research shows that supporting cells play a more critical role in hearing than they get credit for.

In fact, he says, efforts to restore hearing by making new hair cells out of supporting cells may fail, unless researchers also work to replace the supporting cells. “We had known that losing hair cells results in deafness, and there has been an effort to find a way to regenerated these specialized cells. One idea has been to induce supporting cells to become hair cells. Now we discover that losing supporting cells kills hair cells as well,” he explains.

“And now, we’ve found that there’s an intrinsic regenerative potential in the very early days of life that we could harness as we work to cure deafness,” continues Corfas, who is a professor in the U-M Department of Otolaryngology. “This is relevant to many forms of inherited and congenital deafness, and hearing loss due to age and noise exposure. If we can identify the molecules that are responsible for this regeneration, we may be able to turn back the clock inside these ears and regenerate lost cells.”

In the study, the “understudy” supporting cells found in a structure called the greater epithelial ridge transformed into full-fledged supporting cells after the researchers destroyed the mice’s own supporting cells with a precisely targeted toxin that didn’t affect hair cells. The new cells differentiated into the kinds that had been lost, called inner border cells and inner phalangeal cells.

“Hair cell loss can be a consequence of supporting cell dysfunctional or loss, suggesting that in many cases deafness could be primarily a supporting cell disease,” says Corfas. “Understanding the mechanisms that underlie these processes should help in the development of regenerative medicine strategies to treat deafness and vestibular disorders.”

Making sure that the inner ear has enough supporting cells, which themselves can transform into hair cells, will be a critical upstream step of any regenerative medicine approaches, he says.

Corfas and his colleagues continue to study the phenomenon, and hope to find drugs that can trigger the same regenerative powers that they saw in the newborn mice.

The research was a partnership between Corfas’ team at U-M and that of Jian Zuo, Ph.D., of St. Jude, and the two share senior authorship. Marcia M. Mellado Lagarde, Ph.D. of St. Jude and Guoqiang Wan, Ph.D., of U-M are co-first authors. Additional authors are LingLi Zhang of St. Jude, Corfas’ former colleagues at Harvard University Angelica R. Gigliello and John J. McInnis; and Yingxin Zhang and Dwight Bergles, both of Johns Hopkins University.

The research was funded by a Sir Henry Wellcome Fellowship, a Hearing Health Foundation Emerging Research Grant, the Boston Children’s Hospital Otolaryngology Foundation, National Institutes of Health grants DC004820, HD18655, DC006471, and CA21765; Office of Naval Research Grants N000140911014, N000141210191, and N000141210775, and by the American Lebanese Syrian Associated Charities of St. Jude Children’s Research Hospital.

The above post is reprinted from materials provided by University of Michigan Health System. 

  We need your help in funding the exciting work of hearing and balance scientists. 

To donate today to Hearing Health Foundation and support groundbreaking research, visit hhf.org/name-a-grant.

How Hearing Loss Affects Other Aspects of Your Health

By Patricia Sarmiento

A few years ago, my dad began experiencing hearing loss. He worked in loud factories all his life. And while in recent years he began wearing ear protection, I think there were many days on the job where he didn’t use any. As he grew older, all that time without ear protection took its toll.

Prior to his experiences with hearing loss, I must admit that I didn’t know much about it. As he began going through the necessary steps, like getting fitted for hearing aids, I began to look into how hearing loss can affect our overall health. Here’s what I found:

Falls: This was my first area of concern when my dad’s hearing loss was diagnosed. I knew that our ears play an important role in our balance. However, I was surprised to see how significantly one’s chances of falling increased with their hearing loss. WhittierHearing.com cites a study that found that even just mild hearing loss meant you were “three times more likely to have a history of falling.” Of course, the older someone is the more dangerous these falls can be. My dad was lucky in that his hearing loss didn’t ever seem to affect him in this way. But if you have a loved one who has fallen or is experiencing balance issues, get their hearing checked!

Depression. We actually began suspecting that my dad was experiencing hearing loss long before he began seeking treatment for it. I think he was simply too proud to admit that he was having problems. We had to repeat ourselves to him and sometimes at family gatherings he would withdraw altogether. It was when he stopped going to his weekly Men’s Breakfast at our church that we knew something was going on.

While my dad received treatment before his hearing loss really began to take a toll on his mental health, I can definitely see how it could lead to depression. People experiencing hearing loss may experience poorer quality of life, isolation and reduced social activity.

Dementia. Through my research, I found out that in older adults there is a connection between hearing loss and dementia and Alzheimer’s. Those with mild hearing impairment are nearly twice as likely to develop dementia compared to those with normal hearing. The risk increases three-fold for those with moderate hearing loss, and five-fold for those with severe impairment. It isn’t yet clear what causes the connection, but the article says some researchers believe it may result from those with hearing loss straining “to decode sounds,” which may take its toll on the brain.

So, what can you do to protect your hearing? I’d like to suggest going for a swim. Here’s why: This guide on swimming and heart health notes what an excellent cardiovascular and full body workout swimming can be. That’s important because there have been many studies showing a connection between heart health and hearing. Yet another reason to be sure you’re getting plenty of exercise!

Patricia Sarmiento loves swimming and running. She channels her love of fitness and wellness into blogging about health and health-related topics. She played sports in high school and college and continues to make living an active lifestyle a goal for her and her family. She lives with her husband, two children, and their Shih Tzu in Maryland.

See our Hearing Health story, “Have a Hearing Loss, Have Another Health Issue?” for more information about health conditions associated with hearing loss.

Does noise stress you out?

By Kathi Mestayer

Yes, it does.  In fact, noise stresses most people (and even many animals). 

But what is noise? My favorite definition is in the glossary of “Sound Matters,” a 2012 publication of the General Services Administration’s (GSA) Public Buildings Service:

“Noise: Any undesired sound.”

So, if noise is undesired, it’s not that surprising that it’s stressful, right? In an article in Noise and Health, “Is There Evidence That Environmental Noise Is Immunotoxic?,” the author, Deepak Prasher, doesn’t mince words: “It is clear that noise is a stressor. The physiological response to noise as a stressor is no different from any other nonspecific physical stressor.” So, how does noise stress us out?

Danger! Danger! Warning! Warning!

Noise triggers a stress response in the amygdala, a region of the brainstem. Our amygdala learns, over time, what sounds might signal impending danger. When one is detected, the amygdala triggers a release of cortisol (a stress hormone) and an involuntary startle reaction. In his book, The Universal Sense: How Hearing Shapes the Mind, neuroscientist Seth Horowitz explains, “The auditory startle circuit is a very successful evolutionary adaptation to an unseen event. It lets us get our bearings and get the hell out of there, or at least widen our attention to figure out what the noise was.”

Cortisol affects us in many ways. According to Prasher, “In the acute stress reaction to an immediate threat, the secretion of stress hormones results in increased heart rate and blood pressure, a rapid release of energy in the bloodstream, reduced metabolism with a decrease in salivary and gastrointestinal activity, reduction in sex hormones, and activation of some immune functions.”

Over time, stress (often from transportation and industrial noise) can be particularly toxic. “This model of reactivity in terms of noise-induced stress has been implicated in the development of disorders of the cardiovascular system, sleep, learning, memory, motivation, problem-solving, aggression, and annoyance,” Prasher writes. If you think you’re getting used to that highway noise, think again.

Hearing loss and noise

So, people with hearing loss must be less sensitive to noise, right? Unfortunately, no—less hearing doesn’t mean higher noise tolerance. Research has been done on noise sensitivity and whether it correlates with a person’s audiogram. Here’s a summary of findings from the 2012 issue of Noise & Health:

“In the study of Stansfeld (1992), no significant differences were found in noise sensitivity between those with normal threshold of hearing and those with threshold impairment according to pure tone threshold audiometry. Likewise, Ellermeier et al. (2001) found no significant differences between two groups of low and high noise sensitivity in threshold levels, intensity discrimination, auditory reaction time or exponents for loudness functions. Our finding that the average hearing thresholds did not differ in noise sensitive and non-noise sensitive subjects is in concordance with previous studies.”

Anecdotally, this matches my audiologist’s observation that noise sensitivity is not correlated with our degree of hearing loss. “I always have to do a ‘sudden noise’ test with every person whose hearing aids I program before they leave my office. I can never predict who’s going to jump out of their skin and who’s not,” she says. 

In case you’re wondering, I jumped.

Staff writer Kathi Mestayer serves on advisory boards for the Virginia Department for the Deaf and Hard of Hearing and the Greater Richmond, Virginia, chapter of the Hearing Loss Association of America. This is adapted from her reader-sponsored work, “Be Hear Now."

Spotlight On: Andy Groves, Ph.D.

Andy Groves, Ph.D.

CURRENT INSTITUTION: 

Baylor College of Medicine, Houston, Texas

EDUCATION:

Undergraduate from the University of Cambridge

Ph.D. from the Ludwig Institute for Cancer Research, London

Postdoc at the California Institute of Technology 

This new feature aims to connect Hearing Health Foundation (HHF) supporters and constituents to its Hearing Restoration Project (HRP) consortium researchers. Spotlight On provides an opportunity to get to know the life and work of the leading researchers working collaboratively in pursuit of a cure for hearing loss and tinnitus. 

What is your area of focus?

I am a developmental biologist who uses the ear as a model system to understand the general problem of embryonic development—how do you form something very complicated from very simple beginnings. The inner ear is a tissue that receives extremely precise instructions to form just the right number of cells in the right place at the right time. My lab studies where the ear comes from embryonically, how the cochlea acquires its exquisite pattern, and why sensory hair cells are not replaced in mammals after damage.

Why did you decide to get in to scientific research?

I always enjoyed biology and chemistry as a kid and thought it would be more fun than studying medicine. I had a very enthusiastic high school biology teacher who loaned me books on biology and evolution, which made an enormous impression. When I was an undergraduate at Cambridge, I was lucky to have two professors who both won Nobel Prizes, and during my senior year I had the opportunity to do research with one of them. After that, scientific research seemed like the only game in town….

Why hearing research?

I started to study ear development as a postdoctoral fellow in the 1990s because it had received very little attention for decades. The ear appeals to my love of extremes in biology: It has one of the most elaborate three-dimensional structures of any organ; it possesses cells of astonishing mechanical sensitivity; and it can detect sounds over a trillion-fold power range. It is also remarkable to think that our entire auditory experience—conversation, music, the natural world—is captured by just a few thousand sensory cells in each ear!

What is the most exciting part of your research?

Experiments can take months or years to carry out. But every now and then you find something new, and the thrill of realizing that you have found out something that no one else in the world knows about is quite addictive.

What do you enjoy doing when you’re not in the lab?

I am a huge music fan and have a large CD collection. Right now my playlist includes Beethoven sonatas played on a fortepiano, some rare Miles Davis live concerts from 1965, and Howlin’ Wolf albums. As a grad student, I sang at Cambridge and with the London Philharmonic Orchestra. I also love reading. Despite living in the U.S. for over two decades, I know very little about its history, so I have been trying to educate myself about the Civil War Era. I just finished reading “The Half Has Never Been Told” by Edward Baptist.

What is a memorable moment from your career?

For me, it is the “firsts”—seeing students or postdocs publish their first paper or when someone in my lab gets their first academic position. The nature of science means that most of what is discovered will become obsolete or surpassed, but the achievements and careers of the people who have come through the lab will hopefully last for much longer.

If you weren’t a scientist, what would you have done?

To be honest, I never had a “plan B.” I love teaching, and so if I had to give up research, it might be nice to teach biology to undergraduates.

Hearing Restoration Project

What has been a highlight from the HRP consortium collaboration?

The biggest help has been having collaborators on hand to do experiments that are outside the scope of my own lab. We recently published a paper with another HRP researcher, Stefan Heller, Ph.D., at Stanford, where he helped us analyze gene expression of single cells in the cochlea. We showed that blocking the Notch pathway could cause new hair cells to form in very young animals, but that this approach stops working as animals get older. The explosion of new technology and techniques means it is harder to do all the experiments you want in your own lab—so collaboration is key.

What do you hope to have happen with the HRP over the next year, two years, five years?

I hope we can begin a large-scale testing of candidate drugs or gene manipulations in the next two years. This initial screening will likely be in cell culture systems or in the zebrafish system that some members of the HRP helped to pioneer. In five years, I hope we have lead compounds that have been validated independently in several HRP labs.

What is needed to help make HRP goals happen?

Frankly, funding to keep our research moving forward. A postdoctoral fellow with five to six years of training starts out on a modest salary of about $45,000, plus $12,000 in benefits. So that’s $57,000 before they even pick up a test tube in the lab. Each person will typically use between $15,000-$20,000 a year in supplies and chemicals. Simply maintaining a single cage of mice for one year costs $210, and my lab can use between 300-500 cages of mice for our experiments! HHF and its donors have been extremely generous in their support, however with additional funding the output from the consortium could be significantly greater and accelerate the pace to a cure.

Which scientist or mentor was the most inspirational?

My two postdoctoral mentors at Caltech, David Anderson and Marianne Bronner, were both instrumental in making me the scientist I am today. As I was moving into the ear field, I was also lucky to meet Ed Rubel while he was on a sabbatical at Caltech and now as a fellow member of the HRP. More broadly, my two scientific heroes are Seymour Benzer and Francis Crick. Both were gifted scientists who laid the foundations of modern biology and were able to make seminal contributions to every field they worked in, from developmental and molecular biology to the study of aging, behavior, and consciousness. 

Your financial support will help ensure we can continue this vital research in order to find a cure for hearing loss and tinnitus in our lifetime. Please donate today to fund the top scientific minds working collaboratively toward a common goal. For more information or to make a donation, email us at info@hhf.org.

Your help provides hope.

Hearing: It Takes Two

By Teresa Nicolson

A major challenge in hearing research is to understand how structures known as ‘hair bundles’ are formed in the cochlea. Hair bundles have a crucial role in the detection of sound and the conversion of mechanical signals (that is, sound waves) into electrical signals. The cochlea contains two types of hair cells – inner and outer – and a hair bundle protrudes from the top of every hair cell. Each hair bundle consists of a collection of smaller hair-like structures called stereocilia that line up in rows within the bundle to form a structure that resembles a staircase (Figure 1). The stereocilia are filled with filaments made of the protein actin.

Figure 1: The roles of the two isoforms of myosin 15 (MYO15) in hair bundles.

Left: Schematic depiction showing the three rows of stereocilia in a normal hair bundle, with the first row (dark green) being the shortest and the third row (pale purple) being the tallest. This difference in height results in a characteristic staircase-like structure. The stereocilia in the first two rows mediate the process of mechanotransduction, and the large isoform of myosin 15 localizes to the tips of these stereocilia; the small isoform is found primarily in the taller stereocilia in the third row. Right: When both isoforms are defective or absent, the stereocilia in the third row do not reach their normal height (top). If the N-terminal extension in the large isoform is absent in mice, hair bundles form normally but some of the stereocilia in the first two rows degenerate in older animals (bottom). The large isoform of myosin 15 has a large extension (shown in orange) at its N-terminus.

Through studies of deaf patients, geneticists have made remarkable progress in identifying genes that are required for hearing (see hereditaryhearingloss.org). Many of the corresponding proteins are important for the function of hair cells and more than a dozen of them have roles in the hair bundle; these proteins include several myosin motor proteins that differ from the conventional myosin motors that are found in muscle cells. Hair cells actually produce two versions (or isoforms) of one of these unconventional myosin motors, myosin 15 (Wang et al., 1998; Liang et al., 1999). One of these isoforms has a large (134kD) extension at its N-terminus, but the role played by this extension in hair cells has long been a mystery.

A clue to the importance of the extension is provided by the fact that mutations in the gene (exon 2) that encodes the additional amino acids in the extension cause deafness in humans (Nal et al., 2007). To explore the role of this extension Jonathan Bird and co-workers – including Qing Fang as first author – have compared mice in which the myosin 15 proteins have the extension (isoform 1) and mice in which they do not (isoform 2; Fang et al., 2015).

Previously our knowledge about the function of myosin 15 was based on studies of mice with a mutant shaker2 gene: this mutation leads to defective hair cells in both the cochlea and the vestibular system, which is the part of the ear that controls balance. (The name shaker was coined to describe the unsteady movements seen in these mice). The shaker2 mutation effects both isoforms of myosin 15 and prevents the stereocilia growing beyond a certain height (Probst et al., 1998). The staircase-like structure seen in normal hair bundles is not seen in the shaker2 mice.

Experiments with an antibody that recognizes both isoforms suggest that myosin 15 is located at the tips of the stereocilia (Belyantseva et al., 2003). The shaker2 phenotype suggests that myosin 15 promotes the growth of stereocilia, presumably by working as an actual motor that interacts with actin filaments (Bird et al., 2014). However, the details of how this happens are not fully understood, although it might depend on proteins that are transported to the growing tip by myosin 15 (Belyantseva et al., 2005; Zampini et al., 2011).

The large isoform of myosin 15 (green) localizes predominately at the tips of short stereocilia (magenta), but not tall stererocilia, in inner hair cells in the cochlea of mice

To examine the role played by the large extension in isoform 1, Fang, Bird and colleagues – who are based at the University of Michigan, the National Institute on Deafness and Other Communication Disorders, and the University of Kentucky – generated an antibody that is specific to this isoform and used it to investigate the effects of deleting the exon 2 gene (Fang et al., 2015). Surprisingly, they found that isoform 1 is restricted to the first two rows of stereocilia in inner hair cells (Figure 1). In outer hair cells, on the other hand, isoform 1 is also found at the tall stereocilia in the third row. As for isoform 2, it is mainly present in the third row in inner hair cells.

Finding the two isoforms in different locations came as a surprise, but it could help to explain why deletion of the N-terminus and shaker2 mutations lead to different phenotypes. Shaker2 mutations affect both isoforms and lead to short hair bundles. Deletion of the N-terminus does not affect the length of stereocilia: rather, the hair bundles develop normally at first, but the first two rows of stereocilia then wither away. This suggests that the large isoform is important for the maintenance of a subset of the stereocilia: in particular, it maintains the stereocilia are involved in converting sound energy into an electrical signal in the inner part of the cochlea.

This conversion process, which is called mechanotransduction, is largely present in both the shaker2 mutants and in the mice in which the N-terminus has been deleted, albeit with some subtle differences. This phenotype suggests that myosin 15 is not directly involved in mechanotransduction: however, it seems that the large isoform of myosin 15 can recognize and accumulate at sites where this process takes place. The localization pattern of myosin 15 observed in the outer hair cells reinforces the idea that some form of membrane tension is required for accumulation of the large isoform.

A similar result was found with another protein (called sans) that is required for growth of stereocilia: deleting sans after hair bundles had fully formed caused the first two rows of stereocilia to shrink over time (Caberlotto et al., 2011). Sans interacts with the mechanotransduction machinery in hair cells (Lefèvre et al., 2008), and the loss of sans has a more dramatic effect on mechanotransduction than the loss of myosin 15. Nevertheless, these two cases suggest that it is possible to uncouple the different roles of various proteins in development and in the subsequent maintenance of mechanically-sensitive stereocilia in hair bundles. It will be interesting to see whether other short bundle mutants may have a similar phenotype, if given the chance.

Paper Acknowledgements

We thank Dennis Drayna, Lisa Cunningham, Katie Kindt and Melanie Barzik for critical reading; and Stacey Cole, Elizabeth Wilson, Joe Duda, Karin Halsey, Lisa Kabara, Jennifer Benson, Stephanie Edelmann, Anastasiia Nelina and Ron Petralia for expert technical assistance. This research was supported by funds from the NIDCD intramural research program DC000039-18 and DC000048-18 (JEB, IAB, TBF), NIDCD extramural funds R01 DC05053 (SAC, GIF, QF, MM, and AAI), R01 DC008861 (AAI, GIF), P30 DC05188 (DFD), the Hearing Health Foundation (MM) and a University of Michigan Barbour Scholarship and James V. Neel Fellowship (QF). We thank the University of Michigan Transgenic Animal Model Core and grants that support them (P30 CA46592), and the animal care staff at each institution.

This post originally appeared on eLife Science on October 6, 2015 in reference to the scientific publication, "The 133-kDa N-terminal domain enables myosin 15 to maintain mechanotransducing stereocilia and is essential for hearing." For the article's references and citations, please click here. 

HHF Celebrates National Protect Your Hearing Month

By Emily Shepard

October marks National Protect Your Hearing Month, part of the American Academy of Audiology’s (AAA) campaign to raise public awareness about hearing protection. Through extensive research and programming such as the Safe and Sound Program, Hearing Health Foundation has contributed greatly to this awareness. To celebrate National Protect Your Hearing Month, HHF has compiled a list of 5 Must Know Facts about Hearing Loss Prevention.

Fact #1: Noise Induced Hearing Loss (NIHL) can be contracted in a variety of environments.  Around 30 million U.S. workers are exposed to hazardous noise levels. The National Institute on Deafness and Other Communication Disorders (NIDCD) reports that 26 million Americans between the ages of 20 and 69- around 15% of the population- have NIHL due to exposure to loud sounds or noise at work or in leisure activities. 60% of military service members have NIHL or tinnitus, or both. Given this huge percentage, it’s unsurprising that active and veteran service members rank hearing loss and tinnitus as their top health concern.  

Fact #2: NIHL is the most preventable type of hearing loss. The measures needed to prevent NIHL are easy and simple. Just remember the following three words: Walk, Block, and Turn. When exposed to loud sounds, walk away. Block noise by wearing earplugs or other hearing protective devices when involved in a loud activity. Turn down the sound on stereos and mp3 devices. These are some of many ways you can help protect your hearing. Ultimately, the idea is to keep an eye (or an ear) on noises that seem hazardous or alarming.   “For more information about how to protect your hearing, please visit our partner’s page, It’s a Noisy Planet. Protect Their Hearing®.

Fact #3:  Half of classical orchestral musicians experience hearing loss. But that doesn’t mean you should! As stated in our blog post, “The Danger From Noise When It Is Actually Music”, musicians practice or perform up to eight hours a day. Sound levels onstage can reach up to 110 decibels (dB), the equivalent of a jackhammer! Prolonged exposure to 85 dB (the sound of heavy traffic), causes hair cells of the inner ear to be permanently damaged and can lead to hearing loss. With an 85 dB minimum for this risk, musicians exposed to jackhammer-levels are in dangerous territory. Attending an orchestra show or any other musically-vibrant production may not put you at the same risk of musicians, but it is still important to take cautionary measures. Find a seat that isn’t too close to the front of the stage and bring earplugs in case the music gets too loud. If the sound becomes especially loud, it might be worthwhile to leave early. Since soundtracks and recordings of shows are often available for purchase, there’s no need to stay out of fear of missing out. Remember, safety should always come first.  

Fact #4: What commonly used portable device is louder than a hair dryer, dishwasher, heavy city traffic, and a subway platform? The correct answer is an MP3 player at maximum volume (105 dB). Listening to your favorite artists or podcasts on blast may seem like a thrill, but there’s nothing fun about subjecting your ears to hazardous noise levels. 1 in 5 teenagers, an age group that frequently uses MP3 players, suffer from hearing loss. The Palo Alto Medical Foundation reports that 12.5% of kids between the ages of 6 and 19 suffer from loss of hearing as a result of using ear phones or earbuds turned to a high volume. So to play it safe, HHF suggests no more than 15 minutes of unprotected exposure at or above 100 decibels.  

Fact #5: Steps to prevent hearing loss should begin the moment someone is born. In 1993, only 5% of newborns were tested at birth for hearing loss. Thanks to HHF’s instrumental role in establishing Universal Newborn Hearing Screening legislation, this percentage increased dramatically. By 2007, 94% of newborns were tested. Early detection of hearing impairments in infants can help to diminish or even eliminate negative impacts that would otherwise harm their future development. Therefore it is important to screen infants for hearing impairments, preferably before they are discharged from the hospital. You can learn about the different types of tests hospitals use to screen infants here.