Hearing Matters Podcast
Welcome to the Hearing Matters Podcast with Blaise Delfino, M.S. - HIS! We combine education, entertainment, and all things hearing aid-related in one ear-pleasing package!
In each episode, we'll unravel the mysteries of the auditory system, decode the latest advancements in hearing technology, and explore the unique challenges faced by individuals with hearing loss. But don't worry, we promise our discussions won't go in one ear and out the other!
From heartwarming personal stories to mind-blowing research breakthroughs, the Hearing Matters Podcast is your go-to destination for all things related to hearing health. Get ready to laugh, learn, and join a vibrant community that believes that hearing matters - because it truly does!
Hearing Matters Podcast
"Your Brain On: Hearing Loss" feat. Dr. Douglas Beck, Dr. Frank Lin, and Dr. Kristin Barry
First and foremost, a special thank you to Drs. Ayesha and Dean Sherzai! Be sure to check out "Your Brain On..." podcast. We're excited to re-release their original work "Your Brain On: Hearing Loss".
Unlock the secrets to preserving cognitive health with the insights from esteemed experts like Dr. Kristin Barry, Dr. Frank Lin, and Dr. Douglas Beck. Discover how hearing loss is not just a standalone issue but intricately linked with cognitive decline. This episode takes you through Dr. Lin's innovative Hearing Number Initiative, which aims to demystify hearing ability assessment, making it as straightforward as checking your blood pressure. Through compelling discussions, we explore why understanding the varying degrees of hearing loss is essential for maintaining cognitive vitality and how advancements in technology are enhancing life quality for those affected.
Explore the fascinating biology behind hearing and listening, as we differentiate between these two crucial processes. Our conversation sheds light on how the inability of inner ear cells to regenerate contributes to gradual hearing loss and why high frequencies are often the first to fade. We dive into the intricacies of the cochlea and its organization, emphasizing how listening is a complex, whole-brain event beyond just perceiving sound. Through the exploration of auditory neuropathy and its impact on hearing tests, we underscore the importance of viewing listening as a holistic brain activity involving emotional and semantic processing.
Learn about the profound connection between hearing loss and dementia, supported by recent groundbreaking studies like ACHIEVE and ENHANCE. These studies reveal how hearing interventions significantly reduce cognitive decline, underscoring the importance of prevention and professional hearing aid fittings. We also discuss the role of technology in mitigating the risks of hearing loss and the potential of advancements such as auditory brainstem implants. With insights from Dr. Kristen Berry on tinnitus, this episode provides a comprehensive understanding of the auditory world and its broader implications for cognitive health.
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Speaker 1:Welcome back to another episode of the Hearing Matters Podcast. I'm founder and host, blaise Delfino, and, as a friendly reminder, this podcast is separate from my work at Starkey. Welcome back to another episode of the Hearing Matters Podcast. I am super excited for this week's episode and it's a little bit different. And here's how this episode was previously released on the podcast your Brain On, and this specific episode is titled your Brain On.
Speaker 1:Hearing your Brain On podcast is hosted by Drs Aisha and Dean Shirzai. Dr Aisha Shirzai is a neurologist and co-director of the Alzheimer's Prevention Program at Loma Linda University, where she leads the lifestyle program for the prevention of neurological diseases. She completed a dual training in preventative medicine and neurology at Loma Linda University and a fellowship in Vascular Neurology and Epidemiology at Columbia University. She is also a trained plant-based culinary artist. Dr Dean Shirzai is co-director of the Alzheimer's Prevention Program at Loma Linda University. Dean trained in Neurology at Georgetown University School of Medicine and completed fellowships in neurodegenerative diseases and dementia at the National Institutes of Health and UC San Diego. He holds a PhD in healthcare leadership with a focus on community health, from Andrews University.
Speaker 1:On their episode of your Brain on Hearing, they were joined by Dr Frank Lin, dr Douglas Beck and Dr Kristen Berry. In this episode, you're going to learn the different kinds and causes of hearing loss, the relationship between aging and hearing loss, the neurological distinction between hearing and listening, the recent groundbreaking studies which have made the link between hearing loss and cognitive decline clearer than ever, how associated conditions like tinnitus impact the brain, and what's coming next in hearing aid technology. So sit back, relax and enjoy.
Speaker 2:There's a whole universe inside the ear the meaning of spoken word, the joy of laughter, the bass of a rock song or the rich strings of an orchestra, the fizzle of crashing waves and the rhythm of earth song. When these sounds reach our brains, they create memories, language, ideas and emotions. Hearing influences our brains in remarkable ways, so when it begins to fade, our minds change too ways.
Speaker 3:So, when it begins to fade, our minds change too. Right now, a quarter way through the 21st century, our understanding of the different stages, types and causes of hearing loss is deeper than ever, and the technology enabling everyone to access this auditory universe is the most powerful and affordable it's ever been.
Speaker 2:In this episode we speak to three incredibly passionate experts in the field of audiology about how the brain makes sense of sounds, the differences between natural and causative hearing loss, how listening is distinct from hearing, and why hearing loss is a leading contributor to cognitive decline and even maybe Alzheimer's.
Speaker 3:And we look ahead to the near future, which, as research, technology and policy continue to strengthen and converge, promises a better life for everyone experiencing hearing loss. This is your Brain on Hearing Loss. First, let's define what hearing loss is.
Speaker 4:Hearing loss implies it's a binary. All of a sudden, one day you have hearing loss right, which we know nothing's far from the truth.
Speaker 2:That's Dr Frank Lin, director of the Cochlear Center for Hearing and Public Health at Johns Hopkins University. The direction Frank took in his medical career was significantly inspired by his grandmother.
Speaker 4:Growing up with my grandmother from midlife. She likely had streptomycin as a child, which is an ototoxic antibiotic which was very common back then, so she always grew up with a pretty marked hearing loss. I thought about my clinical experiences. I thought about my grandmother's experiences, literature studying, quote unquote hearing loss in older adults. It just wasn't done. It was just always this assumption that how can it be important if it's something that everyone develops?
Speaker 3:One of Frank's latest projects, in addition to all the brilliant studies he's led in recent years which we'll speak about later, aims to refine hearing loss down to a numeric skill to make it easier for everyone to measure their capacity for hearing.
Speaker 4:It's called the Hearing Number Initiative. With this app on an Android or iOS smartphone, within about three or four minutes, with a pair of headphones, you'll be able to monitor and you'll be able to measure your hearing number, much like you might know your blood pressure or your weight. The hearing number is just basically how loud your speech sounds have to be for you to hear it. So if your number is zero decibels, it means you can hear really soft sounds, and the higher the number is means the poorer your hearing. You can actually track that longitudinally and what you'll find is that everybody, beginning essentially after your teenage years everybody's hearing, if you monitor that number monotonically declines bit by bit over your lifetime.
Speaker 1:So the term hearing loss is arbitrary.
Speaker 4:So we say arbitrarily, if you look at a 20 decibel cutoff that roughly about 20% of the US population actually has that level. So this initiative now is leveraging essentially existing digital technologies to push all Americans on your smartphone in four minutes to just learn your hearing number and go to track it over your life.
Speaker 2:Generally, hearing loss is defined as mild when your hearing number is between 20 and 40 decibels, moderate from 41 to 60 decibels. And severe between 61 and 80, and profound also called deafness, at upwards of 81 decibels and beyond.
Speaker 3:Dr Douglas Beck. Our next guest for this episode of your Brain On is an audiologist who also happens to be a big fan of Frank's work.
Speaker 5:First of all, frank is a wonderful guy and a genius. He's a neurotologist and he's contributed a lot to these discussions.
Speaker 2:Dr Beck is also a co-host of Hearing Matters podcast, which, with 150 episodes under its belt, is one of the best resources out there for learning about audiology and auditory science and accessible technology.
Speaker 5:One of his early studies in 2011, the Archives of Neurology, frank said that as you go from normal thresholds about 25 dB or better and you get mild hearing loss, you double your risk for dementia over time. With a moderate loss, you triple it. With a severe loss, you quadruple it. So as hearing loss increases, he found greater opportunity and potential for cognitive decline.
Speaker 3:The links between different kinds of hearing loss and cognitive decline will be a core focus of this episode. But first let's explore how our hearing works, so we can better understand what happens when it begins to fade.
Speaker 4:Frank explains to understand what happens when it begins to fade. Frank explains there are four components that dictate our perception of being able to hear and perceive the auditory environment.
Speaker 4:The first component is obviously the sound itself. Little vibrations in the air are characterized by different frequencies high-pitched sounds, low-pitched sounds. The second component is, with the earphones is the conductive portion. The whole job of that conductive hearing process is to collect all those sound vibrations and to convert those sound vibrations into a mechanical energy. Step three is what we call sensor neural hearing, and that's a fancy way of saying. Now what happens is that mechanical energy in the ear bones transmits that energy now into essentially a sonically generated fluid wave in the cochlea. The fluid wave is picked up by these sensory hair cells which detect movement in the fluid to release the electrochemicals that then go to the brain.
Speaker 4:And the fourth step now the brain has to decode that electrical energy back into acoustic media. This all works like literally in real time, right, if you're not hearing as well. It can be related to any of those four components incoming sound the conductive process, the sensor neural process or even the brain decoding process. Now the issue with all mammals, of which we're a part of, is that the cells in our ear that are responsible for transducing and coding sound into neural signals, those cells are all post-bytotic, basically meaning they can't regenerate. Some parts of our brain cells, our cardiac cells, our liver cells, are going to regenerate over a lifetime. Many parts of the inner ear that are the critical machinery for transducing and coding sounds. They're post-bytotic. No one really knows why I mean, for, for example, at avian species, birds, they can actually regenerate parts of the inner ear.
Speaker 4:Just all humans and all mammals, as far as we know, can't, because of that the inner ear is subject over a lifetime of various insults, ranging from just cumulative noise exposure, which can literally damage some of the cells by just, let's say, sheer energy force per se, as well as excitotoxicity. You have too much noise exposure, it leads to too much glutamate release and over time that can be what we call excitotoxic for some of the nerve endings. So we're from microvascular disease, small vessel disease, from lifetime hypertension, diabetes that can damage inner ear, various medications that can be ototoxic in some form.
Speaker 2:Yeah, it's just absolutely amazing that it happens in real time, in milliseconds, and as we get older, we have loss of parts of this range. Yeah, when we talk about age-related hearing loss.
Speaker 4:What we're really talking about is the cochlea that responds for sensor normal hearing, those cells that detect that fluid motion wave and then that convert that fluid motion wave into electrical signal. People begin losing hearing at the higher frequencies first. That just has to do with where those cells are located in the inner ear. We say the inner ear is like tonotopically organized or the keys of a piano. The inner ear that deal with more high frequency sound are more susceptible to damage over time. So we'll begin losing those higher frequencies first before you begin losing some of those lower frequencies.
Speaker 4:It's something you can't hear really. It's more that the signal that your ear is sending to your brain, the inner ear, is sending a slightly more garbled signal to the brain. It sounds like that person is mumbling at you more. You'll notice that under more challenging listening conditions, like when you're in a restaurant. Right, remember the four components of hearing. And the first component, the incoming sound signal, is not good to begin with, and then your inner ear, which is some age-related changes also garbling up even more. That's when you really notice it more. So imagine playing the chord on a piano. Your brain gets it all at one time, right?
Speaker 1:But that chord is actually made up of all these frequencies and intensities.
Speaker 4:So if you're missing some of those, that chord that reaches your brain is a little more fuzzy. That's basically what's happening as we develop age-related hearing loss is that cord per se is not being fully transmitted to the brain with high fidelity, so it sounds garbled basically, Another critical aspect of understanding the interplay between hearing loss, aging and cognitive decline is the distinction between hearing and listening.
Speaker 2:Dr Douglas Beck explains.
Speaker 5:So hearing is perceiving or detecting sound, listening is making sense or comprehending sound. Wernicke's and Broca's are areas of the brain where we process speech, and so these are very, very important for communicative disorders and for understanding. When I hear a click like a pen clicking, or if I tap on the desk, the sound is focused into the ear canal, which is about one inch long in most people, and then it hits the eardrum, the malleus and gestapes. After the sound hits the outer hair cell, it goes to the inner hair cell, it goes across the brainstem and it's perceived in the superior temporal lobe and that's it so very limited, right Sound goes in here, it's perceived here. Lobe, and that's it so very limited right Sound goes in here, it's perceived here.
Speaker 5:When we talk about listening. Listening is far more intense. Listening is a whole brain event. You have the superior temporal lobe, you have the amygdala, you have the hippocampus, where memory occurs, you have the occipital lobe and we have to bring in memory and accent and knowledge of words and pronunciation and all these other emotions. You're having a conversation and it's political and heated. That's going to change the way you interpret those sounds because of the emotional content that overrides some of the semantic content.
Speaker 3:This distinction between how your brain hears and how your brain listens can help us start to comprehend the different ways our auditory windows into the world may change over time, which is so important. The better we understand, the better we'll be prepared when we notice these changes in ourselves and the better we'll be able to appreciate and cater for how those around us sense and perceive the world. Greater knowledge guides, more useful research and more powerful technology.
Speaker 5:Dr Beck highlights how, without the distinction, basic healthcare checks like hearing tests are far less effective. In each of your ears you have between 16,000 and 20,000 neurons that go from the cochlea back to the brain and vice versa. What happens over years is we have something called auditory neuropathy and that just means that those auditory fibers are aging and many of them are degrading over time. If you have even 20% of those fibers intact, when somebody does a hearing test, you're going to press the button or raise your hand, whatever you're doing, because all you need is about 20, 25% of those fibers intact to perceive sound. That's hearing. Hearing is perceiving or detecting sound. That's not enough to get by in the world.
Speaker 5:What separates humans from everybody else, all other beings is not our hearing. Our hearing is actually quite awful. Your dogs, your cats can hear 40,000 Hertz. You and I can only hear up to 20,000 Hertz. What we are fantastic at is listening. Listening is assigning meaning to sound. We have over 10,000 languages and we have accents, and yet we can understand each other if we try really hard. We can express these ideas to each other because of language, not because of hearing.
Speaker 5:In the USA right now this is April of 2024, we have about 335 million people. There was a new study that came out Global Burden of Disease Study. That was talking about 70 million people in the USA with hearing and or listening problems. The way it breaks down is sort of like this you have about 38, 39 million people of the 335 million in the USA that have hearing loss. If we were to do an audiogram, but then there's another 26 million people who have no hearing loss whatsoever in the USA, 26 million who would complain that they can't understand speech and noise and they would complain that they have hearing difficulty.
Speaker 2:So we've talked about how hearing works, how it differs from listening and how our capacity to hear can be measured. Now we're ready to unravel the links between hearing loss and neural degeneration. Dr Beck continues.
Speaker 5:As we age, the central nervous system slows down, what the recent literature in the last five to 10 years is very strongly indicating. Untreated hearing and listening disorders tend to exacerbate cognitive decline. It makes it much more difficult for their brain to absorb all the sensory information around them and if their brain can't do that, that increases the stress on the brain. In order to make sense of the world, we socialize less, our anxiety increases, our communication decreases, our stress increases. There are many studies now that have looked at does untreated hearing loss actually cause dementia? The trend in many published studies is that people with untreated hearing loss tend to do worse over time in executive function, in memory, in visuospatial abilities, and people who are treated tend to do much better Generally.
Speaker 5:2015, dr Amiva out of Bordeaux, france, looked at over 3,000 people, followed for 25 years these people, none of them had hearing tests. These were all self-elected. So of the 3,000 people, they would say do you have hearing loss? So the answer was yes or no. Of the people who said they had hearing loss, some of them got hearing aids. The general trend over 25 years, using the mini mental state exam, which is a very common, well-known cognitive screening test, was the people who self-elected that they had hearing loss and they treated it with hearing aids. They, after 25 years, looked just like the group of people who said they had no hearing loss, whereas the people who had untreated hearing loss over 25 years did much worse in language, in comprehension, in executive function. Worse in language, in comprehension, in executive function, in anxiety, in depression.
Speaker 3:This is such an incredibly important point and the core of our work. Anyone who's familiar with our neuro plan, which stands for nutrition, exercise, unwind, restore, optimize a self-serving acronym easier to remember, of course. These are the five core pillars of brain health, and the O of neuro, which is optimization of cognitive activity, emphasizes the importance of keeping our brain stimulated by engaging in complex, meaningful and purposeful activities that are based on real life.
Speaker 2:Absolutely OPTIMIZE speaks to a brain that's active all the time. The brain is a living environment of 87 billion neurons. Millions of connections disconnect and millions of others reconnect at any one point. What determines that is our interaction with the world around us. Even if you're not interacting with anybody, but hearing the chirping of the birds outside or the cars driving by, that's all activity that stimulates the brain.
Speaker 3:And people who have hearing loss. Slowly and gradually, you see individuals kind of ostracizing themselves from the community, not engaging in a conversation, not knowing what's happening around them and there's a conscious and a subconscious component to that.
Speaker 2:They're subconsciously realizing that they're not connecting and they're withdrawing. And then the other part is when you're not getting stimulation from the brain. There's what they call a Willerian degeneration kind of process. It's critical now that we take it seriously and intervene when we can.
Speaker 3:Now back to Dr Lin for a closer look at the links between hearing loss and reduced cognition.
Speaker 2:The relationship with dementia and hearing has become a centerpiece of this battle of prevention. I would love for you to tell us what the latest data shows as far as hearing loss and cognitive decline in dementia.
Speaker 4:Yeah, so, dean, this is a topic. This is the first topic I really tackled when I joined the faculty in 2010. At Hopkins, in 2010, I came across a paper and the paper was all the way back, dean, from 1989. It was a 21 year old paper. It was a case control paper.
Speaker 4:It took a hundred cases of people with dementia and they looked at the people's level of hearing and they saw there appeared to be this clear relationship between level of hearing loss per se and the odds of having dementia. And, amazingly, when that paper was published in 1989, you think it would have caused a stir, the idea that you know here it was maybe a risk factor to mention that it'd be treatable from my point of view, right Then we'd be very exciting. Amazingly, dean from 1989 to, which was top of 2010, there was really very I mean, like maybe a handful of papers ever looked at it. So in 2010, when I took this topic on, it's really jumped out at me. So in 2010, in 2011, we published the Baltimore Longitudinal Study of Aging and that showed this very clear link between greater hearing loss and the higher the risk of dementia over time. That was published in 2011. That was the first time it had ever been confirmed that hearing loss in a prospective fashion was linked with greater risk of dementia.
Speaker 3:As Dr Lin and his team pushed their research forward, they identified three patterns that could explain why hearing loss contributes to cognitive decline.
Speaker 4:The first idea is this notion of cognitive load the inner ear is sending a garbled signal to the brain. Now the brain may constantly have to work harder. All the time the brain's constantly reallocating resources to dealing with that impoverished, garbled auditory signal, dealing with that impoverished garbled auditory signal. So in this case it's not so much that just a hearing loss causes dementia, but hearing loss uses up that normal cognitive buffer, that cognitive reserve. There's some degree of cognitive reserve which allows for somebody to buffer dementia pathology before it expresses itself phenotypically right. So that's one mechanism.
Speaker 4:The second mechanism hearing loss in of itself can trigger changes in terms of brain structure and function. You have accelerator rates of brain atrophy and or changes in brain neural networks that can have detrimental effects on cognitive function, particularly with a lateral temporal load which handles a lot of auditory processing but also handles other cognitive processes as well. And the third mechanism if you can't hear very well, you're less likely to be cognitively and socially stimulated and engaged. You can imagine over a period of five, 10 years that could have detrimental effects on maintenance of cognitive health over time as well. So those are the three main hypotheses. Since that time period many, many other epidemiologic studies have found the same degree of association different study populations, different investigators, all showing us a very strong link between greater hearing loss and increased risk of cognitive client dementia over time Remarkable.
Speaker 2:The statistics that came out of the studies that you're quoting says that about 10% of dementia can be attributable to hearing loss. I would love for you to expand on that a little bit. So the Lancet.
Speaker 4:Commission on Dementia in 2020, they convened a panel of experts around the world to do a major meta now systematic review of all the different potentially modifiable risk factors for dementia.
Speaker 4:They identified that hearing loss actually is arguably the single largest potentially modifiable risk factor for dementia, counting for fully between 8 to 9% of all dementia cases, and that outpaced any other risk factor, even like high blood pressure, diabetes. And the reason for that is because the epidemiologic literature in the past that looked at hearing loss and increased risk of dementia. Those risk estimates are actually quite large. But on top of that too, hearing loss, like we've talked about before, is not a rare risk factor.
Speaker 4:So you have a relatively powerful risk factor in terms of this risk ratio with dementia risk, and they make that risk factor really common and that's why it rises to the top.
Speaker 3:We asked Dr Lin about some of his more recent research, the ACHIEVE study. If you're a fan of studies being published under fun acronyms, you'll love this one. Achieve stands for Aging and Cognitive Health Evaluation in Elders.
Speaker 4:And it was basically testing this very idea. If we think that hearing loss is indeed linked to dementia through these pathways, does that mean in fact, if you actually treat hearing loss, you actually use hearing aid? Does hearing intervention actually reduce cognitive decline After 10 years? That trial resulted out last year and it was published in the Lancet in July 2023. And lo and behold, we found in this definitive randomized trial among older adults at increased risk for cognitive decline within three years, hearing intervention can reduce that rate of cognitive decline by about 48%.
Speaker 4:It's pretty amazing From a public health point of view, hearing loss is a really common risk factor. There are existing interventions for, let's say, hearing aids which are completely without risk. There's no risk with using a hearing aid, so it's something we're really excited about. It took many years of work.
Speaker 3:By some wonderful coincidence, another audiology study with a fun acronym was published recently the ENHANCE study, which stands for Evaluation of Hearing Aids and Cognitive Effects. As luck would have it, dr Beck covered this research on his Hearing Matters podcast.
Speaker 5:There's another study that came out just about the same time called the ENHANCE study. We just did a story on the Hearing Matters podcast Brilliant, brilliant group of scientists out of Melbourne in Australia. It was different from the ACHIEVE study because at 150 people who were treated with hearing aids and about 100 people with similar profiles, demographics and whatnot and hearing loss, and they were not treated. So now this changes everything because the ACHIEVE study in the at-risk group, yes, there was a big difference, 48%. And now we look at the Melbourne study, the ENHANCE study. That study showed that the people who were treated with hearing aids over three years did not lose any ground in all of the domains evaluated whether it was executive function, speech in noise, communicative abilities, things like that whereas the untreated group did decline over time. So we have more and more and more evidence.
Speaker 5:But I don't want anybody saying, oh well, we're going to put hearing aids on you to prevent decline. That is useful in many people under certain situations, particularly if they're at high risk and particularly we know if it's professionally fitted. We have no knowledge at this point as to over-the-counter hearing aids to get the same result. We don't know. I doubt you would. I think it's much more important that you have significant improvements in audibility, that you have a much better signal-to-noise rate. Just making things louder, that doesn't do it. There are people who need it louder, but most people they're going to say I need sound clearer. I can hear sound, but I can't make sense of it.
Speaker 2:This new research is incredible at face value, but it's even more incredible when you consider that we haven't even started applying the results clinically. We're just now at the start of a new era of auditory science, and the technology at our disposal has never been more powerful. Before we delve into the exciting new directions audiology is headed in, let's take a moment to talk about how you can protect your hearing from causes unrelated to aging, because, as astounding as modern medical treatments are, prevention should always come first. But that's harder than it sounds, because preventative resources aren't always so easy to come by and healthcare information can feel overwhelming and contradictory on today's saturated internet. Dr Beck raised a great point about this during our conversation.
Speaker 5:If you go to the World Health Organization and you look up the quality of healthcare across nations, you'll find that the USA is struggling to be in the mid-30s. It's not to say we don't have the best or the brightest medical schools or scientists or doctors. Indisputably, we have incredible talent in this country, but the problem is that people don't have access to it. Generally speaking, if you have a significant problem for which you're seeking medical help, you go where your insurance tells you to go. What we do is we fix problems rather than prevent problems, is we fix problems rather than prevent problems? And the whole environment of healthcare should be proactive to prevent problems, and I think that's shocking and terrifically unfortunate, and I think we have to do something about that.
Speaker 3:Given the outcomes of the ACHIEVE and ENHANCE studies, hearing aids could, much like lifestyle factors such as nutrition and exercise, be regarded as a preventive measure for cognitive decline. But if we're talking about preventive measures for hearing loss itself, then we arrive at an age-old question Is the music too loud?
Speaker 2:I have two teenagers, bright kids, smart in every way. But you know how teenagers are. They're smart, but still they're immortal. You can damage your hearing by listening to certain types of music as far as frequency and intensity, right yeah, so I think this is something that's always common.
Speaker 4:on Dean, I think you and I are roughly the same age, right? So I'm of the era. I remember the early 80s when the Sony Walkman came out. That was 40 years ago and people were saying the same thing back then and 40 years later. If you look at the prevalence data of hearing loss and now those 40, 50, 60 year olds, it's no worse than it was 40, 50 to 60 years ago, if anything. Actually, a lot of the wireless headphones nowadays we have are honestly probably a lot safer. A lot of times companies Samsung, apple they'll put it in some degree of volume regulators and things like that right, and increasingly, if you're essentially using good wireless earbuds that block out some of the ambient noise, it's even better because you don't have to turn the music as loud to be heard, which is less damage.
Speaker 3:Many smartwatches have a similar feature for ambient noise. If you're wearing an Apple Watch in a loud environment, whether it's a music concert or an underground railway station or a construction site, you'll get a ping alerting you that continuous exposure could damage your ears. Dr Beck elaborates.
Speaker 5:I've been a musician for 50 years and I will tell you that the secret to doing the best you can is, when you go to concerts, when you go to loud sporting events, take these little $1 squishy plugs and you have to roll that thing up. And you roll it up really tiny, because your ear canal is only about four or five millimeters wide. You have to stick that thing in not all the way to your eardrum. You'll hurt yourself, do not do that. But it's got to go in at least a little bit, and then it expands. That's where you're getting hearing protection.
Speaker 5:Now you don't need 85 decibels of hearing protection. When I go to a range, I will use those little cushy things and I'll also use a headset. I don't need to bring it down 50, 60, 70 dB, because what we know about hearing loss? If you listen to 90 decibels of sound for eight hours, that will cause hearing loss. The important thing to know here 90 dB is like me yelling into your ear from about four inches away. It's pretty darn loud, but there's a time and loudness trade-off. So now, if it's 95 dB of loudness, you've only got four hours. If it's 100 dB of loudness, you've only got two hours before you're closing hearing walls At 105 dB, it's one hour. 110 dB, it's 30 minutes. 115 dB you're down to let's call it, eight minutes 120 dB, four minutes. So you see, when you're at a concert you've got 130, 140, 150 dB. If you can bring it down by five or 10 dB, that's very substantial. You've decreased your risk of hearing loss substantially.
Speaker 3:When you think about loud noises damaging your ears, tinnitus the perception of noises or ringing sounds in the ear that aren't really there may come to mind. Though tinnitus or tinnitus isn't defined as a form of hearing loss, it's often, but not always, caused by hearing loss. We asked tinnitus expert Kristen Berry, a researcher out of Curtin University in Australia, about the commonly chronic symptom.
Speaker 2:I don't know if you want this to be known, but you have a very cool, really rad auditory thalamic neuron tattoo.
Speaker 6:Yeah, I do so. My PhD was in the auditory thalamus. I would stimulate the prefrontal cortex and I would record from these auditory thalamic neurons. The auditory thalamus is quite a fun little structure in that when you're recording from them, you can actually play noises to them. If you set it up to the right equipment, they make little noises back so you can identify them in real time. So I spent a lot of time with these cells and so I decided to commemorate when I finally finished with the image of one of these cells and that is what I have tattooed behind my ear.
Speaker 6:For the auditory system there's several forms of tinnitus. So there's sort of this tinnitus that you can actually find a root of and that can be like a pulsatile tinnitus and that can be actually in your ear that might be related to something like some sort of blood pressure or maybe some sort of issue with the middle ear bones. It's important to, if you're experiencing tinnitus, rule out those causative mechanisms. But then there's more, this centralized tinnitus that has a more central nervous system response. That perceptual tinnitus is the one that I'm investigating. Hearing loss has been commonly shown to lead to tinnitus. Not everybody with hearing loss develops tinnitus, but it's common to eventually sometimes cause tinnitus, things like blast exposure. So if you have been in some sort of concussive force event, say maybe a car accident, that could eventually lead to the development of tinnitus. We kind of think of it in the research as a central brain mechanism, a central response to peripheral damage, and that peripheral damage is very often hearing loss or some sort of cochlear trauma.
Speaker 2:And what happens to the brain when somebody's experiencing tinnitus downstream?
Speaker 6:If you look at things like fMRI or other sort of imaging techniques, you can see things like abnormal connections between certain areas of the brain, and so that was part of what prompted the studies that I did looking at things like that prefrontal cortex region. There's a big study by the Lancet that came out showing that one of the highest modulatory risk factors for cognitive decline is hearing loss. It's all sort of really new and its role in tinnitus is incredibly new, but that's all a really really exciting field. Hippocampus and memory is really implicated in dementia, and in the temporal lobe we also have the auditory cortex, so we think the mechanisms might be sort of related and isolated to that temporal cortex.
Speaker 2:Yeah, yeah, and it's so prevalent. The latest data anywhere up to 10% of Americans suffer from some degree of tinnitus right, and I'm assuming that those numbers translate to other communities and cultures as well. Or is that not the case?
Speaker 6:So it's actually super interesting because I'm in Western Australia and we have a very high Aboriginal indigenous population and they suffer from huge rates of conductive hearing loss because they're very prone to otitis media, so ear infections, so they have huge rates of conductive hearing loss. So there does seem to be population difference of certain types of hearing loss.
Speaker 3:Thus the importance of not just more research, but more diverse and inclusive research. Dr Lin also highlighted a fascinating demographic influence on hearing loss.
Speaker 4:One really interesting one is skin color. Skin color is often termed by melanin pigmentation in our skin. You have a corresponding amount of melanin pigment in your inner ear. The melanin in our ear is strongly protective. So you see, in general people who have darker skin are much protected against hearing loss over time than people who are lighter skin. So it's actually arguably one of the strongest demographic factors associated with hearing loss.
Speaker 3:Preventing hearing loss and, in turn, its contribution to cognitive decline, isn't just a matter of avoiding loud noises. Some lifestyle factors which relate to your broader health may contribute to hearing loss too. Dr Lin touched on this.
Speaker 4:The other big ones, probably to some degree, are more like the cardiovascular factors hypertension, diabetes, leading to microvascular disease in our ear and the brain. But you're already addressing those things like exercise, things like that.
Speaker 3:After prevention comes treatment and care, of course, and Dr Beck is in the exciting position of having worked in the audiology space for so long. He's witnessed the advent of previous leaps forward in hearing aid technology and now gets to watch other revolutionary advancements unfold.
Speaker 2:You worked in this field for several years, many, many years. What was the thing that stood out for you in your research? What's the thing that was an aha moment that clarified the field to you so?
Speaker 5:back in the early 80s, early on in my career, I went to the House Ear Institute in Los Angeles and William F House was there. And Dr House is the fellow who brought forward cochlear implants to the whole world. Now I will tell you this and most people won't believe it. You've heard of cochlear implants. People think, oh, that's new. Well, truth of the matter is the first one was done in 1959. And then Bill House in Los Angeles did three in 1960 and 61.
Speaker 5:I got to the House Ear Institute about 20 years later, in the very early 80s, and I saw that patients who had 110, 115 decibel thresholds 40 plus years ago. They were beyond what a hearing aid could help. Their hearing capacity was just awful and they hadn't heard sound in decades and Dr House could implant them with cochlear implants. Back then they were not FDA approved. The FDA didn't approve this until 1986. And again Bill House started doing them in 1961. So it took 25 years for it to get FDA approved and I saw these patients go from there's nothing we can do to help these people to some of them using a phone, and I still have. This is 2024,. One of the patients that I met back then I'm still in touch with and she's been listening through cochlear implants for the last 30 or 40 years and many people have at this point and so you know I started to see how important hearing is, because for the people who had few or no options, their life changed. Seeing the difference the cochlear implants made in people's lives, it was shocking. It was a day and night difference.
Speaker 5:And then just a few years later Dr Bill House and Dr Bill Hitzelberger, the neurosurgeon he worked with, started implanting directly at the brainstem for people who didn't have inner ears and didn't have auditory nerves. Now that's extremely rare. There are people who have something called NF2, neurofibromatosis type 2, also called von Recklinghausen's disease, and they have tumors in their cerebellopontine angle which often to remove those tumors we go translabyrinthine through the ear to take the tumors out. So that takes out their inner ear. But many of them have what's called an auditory brainstem implant. So these are people who don't have intact inner ears. So you can't do a cochlear implant so you bypass the ear entirely. You go to the brainstem. I have a wonderful example of that A very dear friend of mine, mr Matt Hay, and you can see his video at the Hearing Matters podcast and Matt has auditory brainstem implant and talking to him is just like talking to you.
Speaker 3:If the technology and procedures for hearing loss are that astonishing now, just imagine how powerful they'll be in the near future, just a matter of years from now. We asked Dr Lin about what to expect next.
Speaker 4:Hearing aids are so expensive, right, you know? Like three to four thousand dollars per pair of hearing aids. Like, what are you talking about? Part of that was because how they were regulated in the past. The only way you could sell a hearing aid is through a licensed provider, through an ENT or an audiologist. And those FDA regulations made sense 45 years ago because with the technology of 1977, you had to manually tune them with a screwdriver. I'm not joking With digital technology nowadays. It's clearly not true anymore, right? But those laws never kept up until just recently, when we worked with Congress and the National Academies. We got a law passed in Congress a few years ago that was just enacted a year and a half ago, which is re-regulating hearing aids to let them go over the counter.
Speaker 4:We are just seeing the tip now of the innovation that is going to be coming from some of the big tech companies. They're already making high quality wireless earbuds. The idea that those could be converted and essentially the same as an OTC hearing aid makes it very, very powerful. And I'll just mention just one company in particular that's already gone public. I have no financial affiliation with this company is Essilor Lexotica. Essilor Lexotica is $27 billion per year revenue company. They own 30, 40% of the per year revenue company. They own 30, 40% of the world's vision market. They own Ray-Ban, they own Oakley, they own LensCrafters. What they've done now and they're releasing at the end of this year they're entering the market with they look like completely I'm honestly super cool stylish glasses. Right In the front of the glasses are six beamformer microphones. So beamform microphones are microphones that detect sound and in general, if we're trying to pick up signal from noise, the more microphones you have and the farther apart those microphones are apart, the better you can get signal from noise.
Speaker 4:That's why a hearing aid is always very limited, because a hearing aid is sort of tiny sits on your ear and only two little microphones there. If you have six microphones across the front of a pair of glasses that you can't even see, and then also in the temple piece that sits above your ear there's a little embedded speaker, so there's nothing in your ear, not bone conduction. It's amazing the few times I've tried it on, because you have six beam form microphones separated apart by the width of your face. When I try these glasses on and this was a busy restaurant in Milan, and then one time again the showcase floor in the Ximena busy restaurant in Milan, and then one time again the showcase floor in the consumer electronics show in Vegas it's like whoever you look at is what you hear, and the reason why it works so well is pure the physics of signal processing. If you have more microphones, the microphones are further apart. You can extract much better signal from noise. And the future, too, I think what you're going to see too, is increasingly the idea of post-microphone algorithmic processing Some of the big tech companies who are creating wireless headphones that synchronize with your phone automatically. Where there's much more computing power, could you even do some of the post-processing in the smartphone directly and allow for even better algorithmic processing.
Speaker 4:The third one I'll mention, which I'm really excited about too, actually, is the next generation of Bluetooth. Right, so you do have Bluetooth nowadays. It's how you pair your phone with your headphones and things like that. So the next generation of Bluetooth version 5.3, it's called AuraCast, which is already released, but just beginning to be phased in now. The next generation of Bluetooth, auracast, will allow far field sound transmission.
Speaker 4:So what does that mean? Imagine if you're in an airport and there's a TV in the gate but you can't hear it. In the future, you'll be able to pull your phone and, much like you pick out a Wi-Fi signal, you're going to pick out the gate five TV and then it's going to stream the gate five TV sound straight to your wireless earbuds. So you can apply that same system in a theater, in a bar, where there are like four silent TVs you can't turn them all on in a lecture hall. So you can, literally, with a pair of compatible wireless earphones or hearing aids, you'll be able to pick out which sound source you want to listen to. So I think it's all converging right now. So it's a really, really exciting time.
Speaker 3:Truly incredible. So let's summarize with five key points. One hearing loss can be caused by changes to any of the four components of hearing, that's, the incoming sound itself, the conductive process, the sensorineural process or the brain's decoding process.
Speaker 2:Two the cells deeper in the ear which help us perceive higher-pitched frequencies are more susceptible to damage. So we tend to naturally lose our sense of those higher frequencies. First, Three.
Speaker 3:The distinction between hearing and listening can be explained as hearing activates specific parts of the brain, like the superior temporal lobe, but actually listening, understanding and interpreting requires the whole brain.
Speaker 2:Four. There are three main explanations for why hearing loss contributes to cognitive decline. The first your brain is put under excessive stress trying to comprehend garbled auditory signals. The second if you can't hear as well, the parts of your brain responsible for processing sounds will be understimulated, potentially leading to atrophy in those regions. And the third losing your hearing can make you feel isolated from the world, and socializing less can negatively impact your cognition.
Speaker 3:And finally, five new policies which allow more companies to integrate hearing aid tech and other innovations into their devices are ushering in an exciting new era of accessibility. We are so grateful to Dr Franklin, dr Douglas Beck and Dr Kristen Berry for bringing so much clarity and hope to this episode. This has been your Brain on hearing loss. We've been your hosts, drs Aisha and Dean Sherzai. Thank you so much for listening.
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