Chapter 6. Hearing, Balance, Taste, and Smell

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By Neuroskeptic | Many people may be living life without a particular brain region – and not suffering any ill-effects. In a new paper in Neuron, neuroscientists Tali Weiss and colleagues discuss five women who appear to completely lack olfactory bulbs (OB). According to most neuroscience textbooks, no OB should mean no sense of smell, because the OB is believed to be a key relay point for olfactory signals. As Wikipedia puts it: The olfactory bulb transmits smell information from the nose to the brain, and is thus necessary for a proper sense of smell. Scent molecules activate olfactory receptors and signals travel up the olfactory nerves to the olfactory bulb, and then on to the rest of the brain via the olfactory tract. From Wikipedia. However, remarkably, Weiss et al.’s five women seem to have entirely normal sense of smell despite lacking any visible OBs on brain MRI scans. On both subjective and objective measures of olfactory function, these women showed no abnormalities. MRIs showing normal development of olfactory bulbs (A) compared to two women with no visible olfactory bulbs but normal sense of smell (B) & (D) and one woman with no sense of smell (C). From Weiss et al. Fig 1 Weiss et al. came across two of the women serendipitously while carrying out MRI scans for an unrelated project. The other 3 were found among healthy controls in the Human Connectome Project MRI dataset.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26825 - Posted: 11.18.2019

Hate eating certain vegetables? It could be down to your genes, say US scientists who have done some new research. Inheriting two copies of the unpleasant taste gene provides a "ruin-your-day level of bitterness" to foods like broccoli and sprouts, they say. It could explain why some people find it difficult to include enough vegetables in their diet, they suggest. The gene may also make beer, coffee and dark chocolate taste unpleasant. In evolutionary terms, being sensitive to bitter taste may be beneficial - protecting humans from eating things that could be poisonous. But Dr Jennifer Smith and colleagues from the University of Kentucky School of Medicine say it can also mean some people struggle to eat their recommended five-a-day of fresh fruit and veg. Everyone inherits two copies of a taste gene called TAS2R38. It encodes for a protein in the taste receptors on the tongue which allows us to taste bitterness. People who inherit two copies of a variant of the gene TAS2R38, called AVI, are not sensitive to bitter tastes from certain chemicals. Those with one copy of AVI and another called PAV perceive bitter tastes of these chemicals, but not to such an extreme degree as individuals with two copies of PAV, often called "super-tasters", who find the same foods exceptionally bitter. The scientists studied 175 people and found those with two copies of the bitter taste PAV version of the gene ate only small amounts of leafy green vegetables, which are good for the heart. Dr Smith told medics at a meeting of the American Heart Association: "You have to consider how things taste if you really want your patient to follow nutrition guidelines." © 2019 BBC.

Keyword: Chemical Senses (Smell & Taste); Genes & Behavior
Link ID: 26814 - Posted: 11.12.2019

By Veronique Greenwood When a bird preens its feathers, it uses a little of nature’s own pomade: an oil made by glands just above the tail. This oil helps clean and protect the bird’s plumage, but also contains a delicate bouquet of scents. To other birds — potential mates or would-be rivals — these smells carry many messages, not unlike the birdsongs and fancy feathers that are more obvious to human observers. These scents may signal that a bird would be dangerous to encounter or might be ready to mate, or any number of other cues. However, new research using dark-eyed juncos, a common North American bird, suggests that these odoriferous messages may not be entirely of the bird’s own making. In a study published last month in the Journal of Experimental Biology, biologists reported that microbes living peacefully on the birds’ oil glands may play an important role in making the scent molecules involved. That implies that the birds’ microbiomes may influence both the smell and the behavior it provokes in other birds. Birds’ scented messages are the focus of the research of Danielle Whittaker, managing director of the Beacon Center for the Study of Evolution in Action at Michigan State University and an author of the paper. Some years ago, after she gave a talk, Kevin Theis, a colleague who studied scent-producing bacteria living on hyenas and who is a co-author of the new paper, asked her whether she had ever looked at the birds’ microbes. “I had never thought about bacteria at all,” said Dr. Whittaker. “But all the compounds I was describing were known byproducts of bacterial metabolism.” Dr. Whittaker took samples of bacteria living on the oil glands of 10 captive dark-eyed juncos and then injected the glands with an antibiotic. When she compared the microbes before and after the treatment, the results seemed to show that two groups of bacteria in particular had taken a hit from the treatment. Furthermore, when she compared the scent molecules in the oil before and after the treatment, there were significant differences. © 2019 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26812 - Posted: 11.11.2019

Adam Miller · CBC News · New research is shedding light on how the brain interacts with music. It also highlights how challenging it is to study the issue effectively due to the highly personalized nature of how we interpret it. "Music is very subjective," says Dr. Daniel Levitin, a professor of neuroscience and music at McGill University in Montreal and author of the bestselling book This is Your Brain on Music. "People have their own preferences and their own experience and to some extent baggage that they bring to all of this — it is challenging." Levitin says there are more researchers studying the neurological effects of music now than ever before. From 1998 to 2008 there were only four media reports of evidence-based uses of music in research, while from 2009 to 2019 there were 185, Levitin said in a recent paper for the journal Music and Medicine. It's a "great time for music and brain research" because more people are well-trained and skilled at conducting rigorous experiments, according to Levitin. Emerging research reveals challenges A new study by researchers in Germany and Norway used artificial intelligence to analyze levels of "uncertainty" and "surprise" in 80,000 chords from 745 commercially successful pop songs on the U.S. Billboard charts. The research, published Thursday in Current Biology, found that chords provided more pleasure to the listener both when there is uncertainty in anticipating what comes next, and from the surprise the music elicits when the chords deviate from expectations. ©2019 CBC/Radio-Canada

Keyword: Hearing
Link ID: 26807 - Posted: 11.09.2019

By Sofie Bates Some people may be able to smell even without key structures that relay odor information from the nose to the brain. Researchers used brain scans to identify two women who appear to be missing their olfactory bulbs, the only parts of the brain known to receive signals about smell sensations from the nose and send them to other parts of the brain for processing. Both individuals performed similarly to other women with olfactory bulbs on several tests to identify and differentiate odors, the scientists report November 6 in Neuron. The findings challenge conventional views of the olfactory system, and may lead to treatments for people with no sense of smell (SN: 7/2/07). “I’m not sure that our textbook view of how the [olfactory] system works is right,” says Noam Sobel, a neuroscientist at the Weizmann Institute of Science in Rehovot, Israel. MRI scans of the women’s brains revealed that where most people have two olfactory bulbs, these two appeared to have cerebrospinal fluid instead. To the researchers, this indicated that the women didn’t have olfactory bulbs. But Jay Gottfried, a neuroscientist at the University of Pennsylvania who was not involved in the study, says “I am not convinced that the women are indeed missing their bulbs.” Some evidence for olfactory bulbs may be undetectable with MRI, like microscopic structures or olfactory tissue that could be found with antibodies, he says. © Society for Science & the Public 2000–2019

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26800 - Posted: 11.07.2019

By Jon Cohen On a lightly snowing Sunday evening, a potential participant in Denis Rebrikov’s controversial plans to create gene-edited babies meets with me at a restaurant in a Moscow suburb. She does not want to be identified beyond her patronymic, Yevgenievna. We sit at a corner table in an empty upstairs section of the restaurant while live Georgian music plays downstairs. Yevgenievna, in her late 20s, cannot hear it—or any music. She has been deaf since birth. But with the help of a hearing aid that’s linked to a wireless microphone, which she places on the table, she can hear some sounds, and she is adept at reading lips. She speaks to me primarily in Russian, through a translator, but she is also conversant in English. Yevgenievna and her husband, who is partially deaf, want to have children who will not inherit hearing problems. There is nothing illicit about our discussion: Russia has no clear regulations prohibiting Rebrikov’s plan to correct the deafness mutation in an in vitro fertilization (IVF) embryo. But Yevgenievna is uneasy about publicity. “We were told if we become the first couple to do this experiment we’ll become famous, and HBO already tried to reach me,” Yevgenievna says. “I don’t want to be well known like an actor and have people bother me.” She is also deeply ambivalent about the procedure itself, a pioneering and potentially risky use of the CRISPR genome editor. The couple met on vk.com, a Russian Facebook of sorts, in a chat room for people who are hearing impaired. Her husband could hear until he was 15 years old, and still gets by with hearing aids. They have a daughter—Yevgenievna asks me not to reveal her age—who failed a hearing test at birth. Doctors initially believed it was likely a temporary problem produced by having a cesarean section, but 1 month later, her parents took her to a specialized hearing clinic. “We were told our daughter had zero hearing,” Yevgenievna says. “I was shocked, and we cried.” © 2019 American Association for the Advancement of Science.

Keyword: Hearing; Genes & Behavior
Link ID: 26732 - Posted: 10.22.2019

By Kelly Servick The brain has a way of repurposing unused real estate. When a sense like sight is missing, corresponding brain regions can adapt to process new input, including sound or touch. Now, a study of blind people who use echolocation—making clicks with their mouths to judge the location of objects when sound bounces back—reveals a degree of neural repurposing never before documented. The research shows that a brain area normally devoted to the earliest stages of visual processing can use the same organizing principles to interpret echoes as it would to interpret signals from the eye. In sighted people, messages from the retina are relayed to a region at the back of the brain called the primary visual cortex. We know the layout of this brain region corresponds to the layout of physical space around us: Points that are next to each other in our environment project onto neighboring points on the retina and activate neighboring points in the primary visual cortex. In the new study, researchers wanted to know whether blind echolocators used this same type of spatial mapping in the primary visual cortex to process echoes. The researchers asked blind and sighted people to listen to recordings of a clicking sound bouncing off an object placed at different locations in a room while they lay in a functional magnetic resonance imaging scanner. The researchers found that expert echolocators—unlike sighted people and blind people who don’t use echolocation—showed activation in the primary visual cortex similar to that of sighted people looking at visual stimuli. © 2019 American Association for the Advancement of Science.

Keyword: Hearing; Learning & Memory
Link ID: 26663 - Posted: 10.02.2019

By Shraddha Chakradhar, Rockefeller University neuroscientist Vanessa Ruta was just named a member of the latest class of MacArthur “Genius” grant winners. The fellowship offers a five-year grant of $625,000 to individuals “who show exceptional creativity in their work and the prospect for still more in the future,” according to the MacArthur Foundation. Fortuitously, or perhaps by design, creativity has been a guiding principle for Ruta, 45, and her work. Both her parents were visual artists, and Ruta herself grew up as a ballet dancer—and at one point considered it a career path. After making the switch to science, however, she says that creativity—and the freedom that comes with it—still plays a big part in how she goes about her work. Her research now involves better understanding how the nervous system takes in external cues such as smell and processes these stimuli to inspire various behaviors. Advertisement STAT spoke with Ruta to learn more about her life and work. This interview has been lightly edited and condensed. Both your parents were artists. Did they influence how you work? I was strongly influenced by their creative process, which is parallel to how scientists work. There’s a kind of honing in your craft. It’s obvious in the artistic endeavors, whether it’s practicing dancing or something else. But it’s also there in the sciences—you have to be disciplined about pushing through with your experiments. © 2019 Scientific American

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26654 - Posted: 09.28.2019

Emily Makowski When we eat sour food, we instantaneously react due to a taste-sensing circuit between the tongue and the brain. Two papers published today (September 19)—one in Cell and the other in Current Biology—show that the otopetrin-1 proton channel in the tongue’s sour taste receptors is one of the components responsible for sour taste sensing in mice. These findings add to the body of sour taste research “from the molecular level, of how these protons are transported, up to the level of how the mice are able to taste it,” says Lucie Delemotte, a computational biophysicist at KTH Royal Institute of Technology who was not involved with either study. On the tongue, each taste bud contains a cluster of taste receptor cells innervated by a gustatory nerve network. The tips of these cells have a variety of taste molecule-capturing proteins and, in the case of sour detection, proteins that are called proton channels that sense pH. A team led by Charles Zuker at Columbia University Medical Center identified a potential sour taste receptor for the first time in 2006, and he and other researchers have continued to work on clarifying the mechanics and function of that receptor along with other possible sour taste receptors. A breakthrough occurred last year when Emily Liman of the University of Southern California’s lab discovered that otopetrin-1 (also referred to as OTOP1) was a proton channel also implicated in detecting sour tastes. But the researchers stopped short of demonstrating that OTOP1 was required for sour taste sensing in an actual animal—until now. © 1986–2019 The Scientist

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26631 - Posted: 09.21.2019

Nicola Davis Squirrels eavesdrop on the chatter of songbirds to work out whether the appearance of a predator is cause for alarm, researchers have found. Animals including squirrels have previously been found to tune in to cries of alarm from other creatures, while some take note of “all-clear” signals from another species with which they co-exist to assess danger. But the latest study suggests animals may also keep an ear out for everyday chitchat among other species as a way to gauge whether there is trouble afoot. “This study suggests that eavesdropping on public information about safety is more widespread and broader than we originally thought,” said Prof Keith Tarvin, co-author of the study from Oberlin College, Ohio. “It may not require tight ecological relationships that allow individuals to carefully learn the cues provided by other species,” he added, noting that the grey squirrels and songbirds in the study moved from place to place without regard for the other. Writing in the journal Plos One, Tarvin and colleagues reported on how they made their discovery by observing 67 grey squirrels as they pottered about different areas in the parks and residential regions of Oberlin. After 30 seconds of observing a squirrel, researchers played it a recording of the call of a red-tailed hawk, which lasted a couple of seconds – and their behaviour in the next 30 seconds was monitored. © 2019 Guardian News & Media Limited

Keyword: Animal Communication; Hearing
Link ID: 26573 - Posted: 09.05.2019

By Ryan P. Dalton Subject cDa29—well-known yet anonymous—resides somewhere in the north of England. You can almost see it: the peat stacks and old textile mills; the limestone and turf ruins where, on divine calling, Hadrian marked the northernmost reach of the Roman Empire. But even were you there, you wouldn’t see it the way cDa29 does. That’s because cDa29 is tetrachromatic: while most people see their world as a mix of three colors—red, green and blue—cDa29 sees hers in four. Difficult to imagine as that world may be for trichromats, your sense of smell provides access to an even richer world, one painted not in four colors but 400. You can almost smell it: the peat, the mills, the turf. How do your senses build these worlds? They begin with sensory “receptors,” which sit on the surfaces of cells and are activated by specific stimuli. In the case of vision, there are three color photoreceptors in your retina—activated by red, green or blue light. By keeping these receptors separated—such that no two photoreceptors occur together in one cell—your retina can keep track of what colors came from where. As a counterexample, you have a few dozen “bitter receptors” on your tongue, but each bitter taste cell contains several of them. This arrangement allows you to detect many different bitter compounds, but it does not help you distinguish between them. As these examples illustrate, you must both be able to detect a wide range of stimuli and to discriminate between those stimuli—and generally, your senses strike a balance between these two objectives. Ever the romantic, your sense of smell casts aside the suggestion of balance and optimizes for both detection and discrimination. Olfactory neurons in your nose have evolved some 400 odor receptors, and each neuron contains only one. Receptors are tuned to detect a few basic odors apiece: some detect geranium petals or pine needles, while others detect the by-products of putrefaction. To organize all this information, your olfactory neurons wire into an “olfactory map” on your brain’s olfactory bulb. Olfactory neurons are one of the few types of neurons that are born throughout your life, and each of the roughly 10,000 such neurons born each day in your nose subsequently wires into the olfactory map in your brain. © 2019 Scientific American

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26492 - Posted: 08.13.2019

Sacha Pfeiffer There's a new smell tingling tourists' noses in the Big Apple, far above the trash bag-lined sidewalks — and this scent is by design. Atop One World Trade Center, New York City's tallest building, a fragrance carrying hints of citrus, beech trees and red maples wafts through the glass-enclosed observatory deck. When the observatory commissioned the custom scent to diffuse through the floor's HVAC system, Managing Director Keith Douglas told the New York Times that he wanted it to elicit a "positive thought," and offer a "a subtle complement to the experience" of visiting the space. But not everyone is keen on the scent. One tourist described the smell as "sickly," according to the Times, which first documented the new aromatic experience in lower Manhattan. It's a marketing strategy businesses are increasingly deploying to lure customers into stores and entice them to stay longer. The smell of cinnamon fills Yankee Candle stores, Subway pumps a doughy bread scent through its vents. International Flavors & Fragrances, the same company that developed clothing chain Abercrombie & Fitch's notoriously pungent "Fierce" cologne, known to linger on clothes long after their purchase, designed One World's scent. "The quickest way to change somebody's mood or behavior is with smell," says Dr. Alan Hirsch, neurological director of the Smell and Taste Treatment and Research Foundation in Chicago. © 2019 npr

Keyword: Chemical Senses (Smell & Taste); Emotions
Link ID: 26487 - Posted: 08.12.2019

Ian Sample Science editor When Snowball the sulphur-crested cockatoo revealed his first dance moves a decade ago he became an instant sensation. The foot-tapping, head-bobbing bird boogied his way on to TV talkshows and commercials and won an impressive internet audience. Block-rocking beaks: Snowball the cockatoo – reviewed by our dance critic Read more But that was merely the start. A new study of the prancing parrot points to a bird at the peak of his creative powers. In performances conducted from the back of an armchair, Snowball pulled 14 distinct moves – a repertoire that would put many humans to shame. Footage of Snowball in action shows him smashing Another One Bites the Dust by Queen and Cyndi Lauper’s Girls Just Wanna Have Fun with a dazzling routine of head-bobs, foot-lifts, body-rolls, poses and headbanging. In one move, named the Vogue, Snowball moves his head from one side of a lifted foot to another. “We were amazed,” said Aniruddh Patel, a psychology professor at Tufts University in Medford, Massachusetts. “There are moves in there, like the Madonna Vogue move, that I just can’t believe.” Advertisement “It seems that dancing to music isn’t purely a product of human culture. The fact that we see this in another animal suggests that if you have a brain with certain cognitive and neural capacities, you are predisposed to dance,” he added. It all started, as some things must, with the Backstreet Boys. In 2008, Patel, who has long studied the origins of musicality, watched a video on the internet of Snowball dancing in time to the band’s track Everybody. He contacted Irena Schulz, who owned the bird shelter where Snowball lived, and with her soon launched a study of Snowball’s dancing prowess. © 2019 Guardian News & Media Limited

Keyword: Hearing; Evolution
Link ID: 26400 - Posted: 07.09.2019

By Richard Klasco, M.D. Q. Please explain positional vertigo. Two of my siblings have woken up in the morning with it. What do you do if you experience it? A. Positional vertigo is a common type of dizziness that can be treated with a simple maneuver. Vertigo is an illusory sensation of motion that is often accompanied by intense nausea. Benign paroxysmal positional vertigo, or B.P.P.V., is the medical term for positional vertigo. It is important to use this term, as there are other types of vertigo with different causes and treatments. B.P.P.V. is caused by microscopic “stones” that are present on the ends of hair follicles in the ear canal and that help you maintain your balance. Vertigo occurs when these stones break off and move from the body of the inner ear into its semicircular canals, which determine our perception of three-dimensional space. This usually occurs as a result of aging or head trauma. Free-floating stones cause the inner ear to give faulty information to the brain about our position in space, creating a false sensation of motion. The mechanism of B.P.P.V. was discovered almost a century ago by the Viennese physician Dr. Robert Bárány, who won a Nobel Prize for his work. In 1979, Dr. John Epley, an ear, nose and throat specialist in Portland, Ore., found that a simple maneuver could treat most cases of B.P.P.V. without the need for drugs or surgery. The Epley maneuver is a series of rapid changes in position of the head that are performed in a doctor’s office. The maneuver repositions stones so they do not cause symptoms. Incidentally, B.P.P.V. has been reported to be cured in some people after they have ridden on roller coasters. © 2019 The New York Times Company

Keyword: Miscellaneous
Link ID: 26365 - Posted: 06.28.2019

By Matthew Hutson LONG BEACH, CALIFORNIA—Spies may soon have another tool to carry out their shadowy missions: a new device that uses sound to “see” around corners. David Lindell Previously, researchers developed gadgets that bounced light waves around corners to catch reflections and see things out of the line of sight. To see whether they could do something similar with sound, another group of scientists built a hardware prototype—a vertical pole adorned with off-the-shelf microphones and small car speakers. The speakers emitted a series of chirps, which bounced off a nearby wall at an angle before hitting a hidden object on another wall—a poster board cutout of the letter H. Scientists then moved their rig bit by bit, each time making more chirps, which bounced back the way they came, into the microphones. Using algorithms from seismic imaging, the system reconstructed a rough image of the letter H (above). The researchers also imaged a setup with the letters L and T and compared their acoustic results with an optical method. The optical method, which requires expensive equipment, failed to reproduce the more-distant L, and it took more than an hour, compared with just 4.5 minutes for the acoustic method. The researchers will present the work here Wednesday at the Computer Vision and Pattern Recognition conference. © 2019 American Association for the Advancement of Science

Keyword: Hearing
Link ID: 26333 - Posted: 06.18.2019

By Virginia Morell Most of us can look at two meal plates and easily tell which one has more food on it. But if someone turns out the lights, we’re out of luck. Not so for Asian elephants. A new study reveals that the pachyderms can judge food quantity merely by using their sense of smell, the first time an animal has been shown to do this. To conduct the research, scientists presented six Asian elephants (Elephas maximus) at an educational sanctuary in Thailand with two opaque, locked buckets containing 11 different ratios of sunflower seeds, a favorite treat. The elephants could not see how many seeds each bucket contained, but they could smell the contents through small holes in the lids. The animals chose the bucket with the greater quantity of food 59% to 82% of the time, the team reports today in the Proceedings of the National Academy of Sciences. (Even dogs, with their famed sense of smell, fail this test, other research has shown.) The discovery makes sense, the scientists say, because elephants are known to have the highest number of genes associated with olfactory reception of any species (about 2000 versus dogs’ 811). They can distinguish between the scent of Maasai pastoralists and Kamba farmers, and rely on their sense of smell to navigate long distances to find food and water (up to 19.2 kilometers). The researchers hope their findings could help mitigate human-elephant conflicts in Asia and Africa, because wandering herds use odors to decide where to travel; enticing scents might help lure them away from agricultural fields, for instance. © 2019 American Association for the Advancement of Science

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26293 - Posted: 06.04.2019

Kerry Grens In mice whose sense of smell has been disabled, a squirt of stem cells into the nose can restore olfaction, researchers report today (May 30) in Stem Cell Reports. The introduced “globose basal cells,” which are precursors to smell-sensing neurons, engrafted in the nose, matured into nerve cells, and sent axons to the mice’s olfactory bulbs in the brain. “We were a bit surprised to find that cells could engraft fairly robustly with a simple nose drop delivery,” senior author Bradley Goldstein of the University of Miami Miller School of Medicine says in a press release. “To be potentially useful in humans, the main hurdle would be to identify a source of cells capable of engrafting, differentiating into olfactory neurons, and properly connecting to the olfactory bulbs of the brain. Further, one would need to define what clinical situations might be appropriate, rather than the animal model of acute olfactory injury.” Goldstein and others have independently tried stem cell therapies to restore olfaction in animals previously, but he and his coauthors note in their study that it’s been difficult to determine whether the regained function came from the transplant or from endogenous repair stimulated by the experimental injury to induce a loss of olfaction. So his team developed a mouse whose resident globose basal cells only made nonfunctional neurons, and any restoration of smell would be attributed to the introduced cells. © 1986–2019 The Scientist

Keyword: Chemical Senses (Smell & Taste); Stem Cells
Link ID: 26285 - Posted: 06.01.2019

Hannah Devlin Science correspondent A mind-controlled hearing aid that allows the wearer to focus on particular voices has been created by scientists, who say it could transform the ability of those with hearing impairments to cope with noisy environments. The device mimics the brain’s natural ability to single out and amplify one voice against background conversation. Until now, even the most advanced hearing aids work by boosting all voices at once, which can be experienced as a cacophony of sound for the wearer, especially in crowded environments. Nima Mesgarani, who led the latest advance at Columbia University in New York, said: “The brain area that processes sound is extraordinarily sensitive and powerful. It can amplify one voice over others, seemingly effortlessly, while today’s hearing aids still pale in comparison.” This can severely hinder a wearer’s ability to join in conversations, making busy social occasions particularly challenging. Scientists have been working for years to resolve this problem, known as the cocktail party effect. The brain-controlled hearing aid appears to have cracked the problem using a combination of artificial intelligence and sensors designed to monitor the listener’s brain activity. The hearing aid first uses an algorithm to automatically separate the voices of multiple speakers. It then compares these audio tracks to the brain activity of the listener. Previous work by Mesgarani’s lab found that it is possible to identify which person someone is paying attention to, as their brain activity tracks the sound waves of that voice most closely. © 2019 Guardian News & Media Limited

Keyword: Hearing
Link ID: 26247 - Posted: 05.18.2019

By Maggie Koerth-Baker Where is the loudest place in America? You might think New York City, or a major airport hub, or a concert you have suddenly become too old to appreciate. But that depends on what kind of noise you’re measuring. Sound is actually a physical thing. What we perceive as noise is the result of air molecules bumping into one another, like a Newton’s cradle toy. That movement eventually reaches our eardrums, which turn that tiny wiggle into an audible signal. But human ears can’t convert all molecular motion to sound. Sometimes the particles are jostling one another too fast. Sometimes they’re too slow. Sometimes, the motion is just happening in the wrong medium — through the Earth, say, instead of through the air. And when you start listening for the sounds we can’t hear, the loudest place in America can end up being right under your feet. Scientists have tools that can detect these “silent” waves, and they’ve found a lot of noise happening all over the U.S. Those noises are made by the cracking of rocks deep in the Earth along natural fault lines and the splashing of whitecaps on the ocean. But they’re also made by our factories, power plants, mines and military. “Any kind of mechanical process is going to generate energetic waves, said Omar Marcillo, staff scientist at Los Alamos National Laboratory. “Some of that goes through the atmosphere as acoustic waves, and some goes through the ground as seismic waves.” Marcillo’s work focuses on the seismic. © 2019 ABC News Internet Ventures.

Keyword: Hearing
Link ID: 26227 - Posted: 05.11.2019

By Heather Murphy The scent of lily of the valley cannot be easily bottled. For decades companies that make soap, lotions and perfumes have relied on a chemical called bourgeonal to imbue their products with the sweet smell of the little white flowers. A tiny drop can be extraordinarily intense. If you can smell it at all, that is. For a small percentage of people, it fails to register as anything. Similarly, the earthy compound 2-ethylfenchol, present in beets, is so powerful for some people that a small chunk of the root vegetable smells like a heap of dirt. For others, that same compound is as undetectable as the scent of bottled water. These — and dozens of other differences in scent perception — are detailed in a new study, published this week in the journal PNAS. The work provides new evidence of how extraordinarily different one person’s “smellscape” may be from another’s. It’s not that some people are generally better smellers, like someone else may have better eyesight, it’s that any one person might experience certain scents more intensely than their peers. “We’re all smelling things a little bit differently,” said Steven Munger, director of The Center for Smell and Taste at the University of Florida, who was not involved in the study. The scientists who conducted the study looked for patterns in subjects’ genetic code that could explain these olfactory differences. They were surprised to find that a single genetic mutation was linked to differences in perception of the lily of the valley scent, beet’s earthiness, the intensity of whiskey’s smokiness along with dozens of other scents. “I think it’s a very important finding,” said Stavros Lomvardas, a neuroscientist at Columbia University’s Zuckerman Institute, who was not involved in the research either. The study was conducted in a large room at Rockefeller University in New York City. Around 300 subjects were invited to sit in front of a computer screen surrounded by 150 jars of assorted odors. The screen alerted them to which jar sniff at any given time, and they then rated the intensity of each on a scale from 1 (extremely weak) to 7 (extremely strong) and pleasantness from 1 (extremely unpleasant) to 7 (extremely pleasant). © 2019 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Genes & Behavior
Link ID: 26203 - Posted: 05.03.2019