Chapter 9. Hearing, Vestibular Perception, Taste, and Smell

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By James Gorman In the world of noses, the elephant’s trunk clearly stands out for its size, flexibility, strength and slightly creepy gripping ability. Go ahead, try to pluck a leaf with your nostrils and see how you fare.So perhaps it should come as no surprise that the elephant’s sense of smell is also outstanding. Past studies have shown that elephants have more scent receptors than any other mammal. And in other experiments, researchers following up reports that elephants in Angola were avoiding minefields found that they could detect TNT. Another report concluded that elephants could use scent clues to tell the difference between two Kenyan tribes, the Maasai, who traditionally speared them, and the Kamba, who did not. The elephants apparently used these clues to help them avoid the Maasai. The latest bit of research adds to the evidence by showing how they use their great sense of smell in choosing food. Elephants often must find vegetation and water at a distance, and they also distinguish between fairly similar plants once they reach a clump of likely vegetation. It seemed that they probably used their sense of smell, but Melissa Schmitt, a researcher at the University of KwaZulu-Natal in South Africa, and her colleagues wanted to see how good they were. So she tested them at close range, using two buckets with two different hidden foods. They easily picked out the bucket with leaves from plants they enjoyed, say wild pear, and avoided ones they didn’t like, wild olive, for instance. © 2018 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 25105 - Posted: 06.19.2018

By JoAnna Klein You’d think that narwhals couldn’t be more enchanting. These elusive, ice-dodging, deep-diving whales have 10-foot snaggletoothed tusks, and they see with sound. But then there’s the narwhal of east Greenland. It’s kind of the narwhal of narwhals. “Because they’re so hard to access, we honestly hardly knew anything,” said Susanna Blackwell, who studies the effects of human sounds on marine mammals for Greenridge Sciences. “It’s an animal that’s been hidden from civilization for an awful long time.” Their genes are only slightly different than their western cousins. And since glaciers separated them some 10,000 years ago, this smaller population of about 6,000 narwhals, has lived relatively free from human contact amid sharp cliffs and mile-wide glaciers that break into huge, bobbing icebergs. But as the ocean warms, ice caps melt and summers get longer in the Arctic, the once inaccessible habitat of east Greenland narwhals is opening up to scientists — as well as cruise ships and prospectors interested in minerals or offshore drilling. And because toothed whales like narwhals use sounds to orient themselves, Dr. Blackwell worries this potential activity will disturb the narwhal’s acoustic way of life. So she and a team attached acoustic sensors to narwhals to monitor their behavior while human sounds are still scarce. What they found, published Wednesday in a paper in the journal PLOS One, will be used as a baseline behavior for an upcoming study to test how narwhals respond to air gun blasts similar to the ones used by oil surveyors, and may help protect them in the future. Narwhals live only in the Arctic, where it’s dark much of the time, diving thousands of feet to hunt, where it’s dark all of the time. Scientists knew they used acoustics to echolocate and communicate from studies done on narwhals in west Greenland or Canada, but they didn’t know much about the sounds of individual narwhals, especially the east Greenland population. © 2018 The New York Times Company

Keyword: Animal Communication; Hearing
Link ID: 25090 - Posted: 06.14.2018

By Matt Warren Not getting eaten is at the top of the to-do list for most members of the animal kingdom. Now, a new study suggests several species of dolphins can tell when they’re in danger of becoming a killer whale’s dinner—simply by eavesdropping on their calls. Risso’s dolphins and short-finned pilot whales are frequently devoured when they live alongside mammal-eating orcas. To find out whether the dolphins can work out when they are in danger, researchers played recordings of killer whale calls underwater to 10 pilot whales off the coast of North Carolina and four Risso’s dolphins swimming near Southern California. The animals didn’t respond to many of the killer whale sounds, but a subset of the calls provoked a strong reaction in both species: Risso’s dolphins rapidly fled, ending up more than 10 kilometers away from where the sounds were played. Pilot whales, on the other hand, called to each other and formed a tight group before diving directly toward the sound, the researchers report today in the Journal of Experimental Biology. The calls that provoked the responses all contained multiple irregular features, such as harsh and noisy sounds or two distinct frequencies at once. The researchers hypothesize that these kinds of calls could be used by groups of killer whales to communicate during hunting—a clear sign for any potential prey in the area to take action. © 2018 American Association for the Advancement of Science

Keyword: Animal Communication; Hearing
Link ID: 25082 - Posted: 06.13.2018

By David Noonan Neuroscientist James Hudspeth has basically been living inside the human ear for close to 50 years. In that time Hudspeth, head of the Laboratory of Sensory Neuroscience at The Rockefeller University, has dramatically advanced scientists’ understanding of how the ear and brain work together to process sound. Last week his decades of groundbreaking research were recognized by the Norwegian Academy of Science, which awarded him the million-dollar Kavli Prize in Neuroscience. Hudspeth shared the prize with two other hearing researchers: Robert Fettiplace from the University of Wisconsin–Madison and Christine Petit from the Pasteur Institute in Paris. Advertisement As Hudspeth explored the neural mechanisms of hearing over the years, he developed a special appreciation for the intricate anatomy of the inner ear—an appreciation that transcends the laboratory. “I think we as scientists tend to underemphasize the aesthetic aspect of science,” he says. “Yes, science is the disinterested investigation into the nature of things. But it is more like art than not. It’s something that one does for the beauty of it, and in the hope of understanding what has heretofore been hidden. Here’s something incredibly beautiful, like the inner ear, performing a really remarkable function. How can that be? How does it do it?” After learning of his Kavli Prize on Thursday, Hudspeth spoke with Scientific American about his work and how the brain transforms physical vibration into the experience of a symphony. © 2018 Scientific American

Keyword: Hearing
Link ID: 25055 - Posted: 06.04.2018

Nicola Davis From whispering sweet nothings to hoping for sweet dreams, sugariness and pleasure have long been bound together. Now scientists studying the brains of mice have revealed why, unpicking the pathways in the brain which result in sweet foods being perceived as nice and bitter foods as nasty. What’s more, they have managed to tinker with these routes so that mice get a kick out of a tasteless substance such as water, and have even managed to switch off such judgments completely. Researchers say the finding may help with the search for treatments for eating disorders. “The very concept of sweet, the very word sweet, implies this goodness, this reward, this craving that we link to it, and similarly bitter on the other side has an immediate meaning to it. So we wanted to know, how does the brain encode meaning on sensory experience?” said Charles Zuker, lead author of the research from Columbia University’s Zuckerman Institute. Advertisement While the work was carried out in mice, Zuker said there could be parallels for the human brain and that understanding the brain circuits involved in taste and our responses to it might eventually open up the possibility of tinkering with our own responses to certain foods – including sugar cravings. © 2018 Guardian News and Media Limited

Keyword: Chemical Senses (Smell & Taste); Obesity
Link ID: 25041 - Posted: 05.31.2018

By Abby Olena Activating or suppressing neuronal activity with ultrasound has shown promise both in the lab and the clinic, based on the ability to focus noninvasive, high-frequency sound waves on specific brain areas. But in mice and guinea pigs, it appears that the technique has effects that scientists didn’t expect. In two studies published today (May 24) in Neuron, researchers demonstrate that ultrasound activates the brains of rodents by stimulating an auditory response—not, as researchers had presumed, only the specific neurons where the ultrasound is focused. “These papers are a very good warning to folks who are trying to use ultrasound as a tool to manipulate brain activity,” says Raag Airan, a neuroradiologist and researcher at Stanford University Medical Center who did not participate in either study, but coauthored an accompanying commentary. “In doing these experiments going forward [the hearing component] is something that every single experimenter is going to have to think about and control,” he adds. Over the past decade, researchers have used ultrasound to elicit electrical responses from cells in culture and motor and sensory responses from the brains of rodents and primates. Clinicians have also used so-called ultrasonic neuromodulation to treat movement disorders. But the mechanism by which high frequency sound waves work to exert their influence is not well understood. © 1986-2018 The Scientist

Keyword: Hearing
Link ID: 25025 - Posted: 05.26.2018

By Chris Buckley and Gardiner Harris BEIJING — An American government employee posted in southern China has signs of possible brain injury after reporting disturbing sounds and sensations, the State Department said on Wednesday, in events that seemed to draw parallels with mysterious ailments that struck American diplomats in Cuba. The State Department warning, issued through the United States Consulate in Guangzhou, a city in southern China, advised American citizens in China to seek medical help if they felt similar symptoms. But it said that no other cases had been reported. “A U.S. government employee in China recently reported subtle and vague, but abnormal, sensations of sound and pressure,” the health alert said. “We do not currently know what caused the reported symptoms and we are not aware of any similar situations in China, either inside or outside of the diplomatic community.” The employee was working in Guangzhou, and “reported experiencing a variety of physical symptoms” from late 2017 until April, Jinnie Lee, a spokeswoman for the United States Embassy in Beijing, said in an emailed response to questions. Secretary of State Mike Pompeo told the House Foreign Affairs Committee on Wednesday that medical teams were heading to Guangzhou to address the issue. “The medical indications are very similar and entirely consistent with the medical indications that have taken place to Americans working in Cuba,” he said. The embassy was told on Friday “that the clinical findings of this evaluation matched mild traumatic brain injury,” according to Ms. Lee, who said she could not reveal any more details to protect the employee’s privacy. Mild traumatic brain injury can show up as headache, dizziness, nausea, poor memory and a general foggy sensation. The Chinese Ministry of Foreign Affairs did not immediately answer faxed questions about the ill American, but Mr. Pompeo said the Trump administration had asked the Chinese government for assistance in an investigation, “and they have committed to honoring their commitments under the Vienna convention.” The Vienna convention requires that countries protect diplomats stationed in their nations. © 2018 The New York Times Company

Keyword: Brain Injury/Concussion; Hearing
Link ID: 25017 - Posted: 05.24.2018

By Maya Salam Three years ago, the internet melted down over the color of a dress. Now an audio file has friends, family members and office mates questioning one another’s hearing, and their own. Is the robot voice saying “Yanny” or “Laurel”? The clip picked up steam after a debate erupted on Reddit this week, and it has since been circulated widely on social media. One Reddit user said: “I hear Laurel and everyone is a liar.” “They are saying they hear ‘Yanny’ because they want attention,” a tweet read. Others claimed they heard one word for a while, then the other — or even both simultaneously. It didn’t take long for the auditory illusion to be referred to as “black magic.” And more than one person online yearned for that simpler time in 2015, when no one could decide whether the mother of the bride wore white and gold or blue and black. It was a social media frenzy in which internet trends and traffic on the topic spiked so high that Wikipedia itself now has a simple entry, “The dress.” Of course, in the grand tradition of internet reportage, we turned to a scientist to make this article legitimately newsworthy. Dr. Jody Kreiman, a principal investigator at the voice perception laboratory at the University of California, Los Angeles, helpfully guessed on Tuesday afternoon that “the acoustic patterns for the utterance are midway between those for the two words.” “The energy concentrations for Ya are similar to those for La,” she said. “N is similar to r; I is close to l.” She cautioned, though, that more analysis would be required to sort out the discrepancy. That did not stop online sleuths from trying to find the answer by manipulating the bass, pitch or volume. © 2018 The New York Times Company

Keyword: Hearing; Attention
Link ID: 24983 - Posted: 05.16.2018

By Kenneth Chang Jerrold Meinwald, who conducted pathbreaking studies of how creatures use chemicals to attract mates, repel predators and send other messages back and forth, died on April 23 at his home in Ithaca, N.Y. He was 91. His death was reported by Cornell University, where Dr. Meinwald had worked for more than 50 years. One project that Dr. Meinwald, an organic chemist, tackled soon after he arrived at Cornell in 1952 was determining what exactly in catnip drives some cats into a playful frenzy. Dr. Meinwald isolated from the plant the active ingredient — a chemical called nepetalactone — and then deduced its structure. He soon discovered an aspect of nepetalactone he had not known about. He was a giving a talk about his chemical findings, and someone had brought in a cat so he could demonstrate the effects. “It turns out not all cats respond,” Dr. Meinwald said in an interview in 2011. “I had a nonresponsive cat. The chemistry was good, but I had not realized you have to pick your subjects carefully.” Dr. Meinwald had a fruitful partnership with Thomas Eisner, an entomologist who joined the Cornell faculty in 1957. That collaboration continued for more than a half-century and established a new field of science, chemical ecology. Dr. Eisner died in 2011 at 81. Biologists had noted decades earlier that organisms produced substances that were not directly needed for the biological processes that maintain life. They suspected that these substances might be used for communications or defense. But it was only in the middle of the 20th century that chemists had the tools to study the substances in detail. © 2018 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 24973 - Posted: 05.15.2018

By Roni Dengler Hoary bats are habitual squawkers. Sporting frosted brown fur á la Guy Fieri, the water balloon–size bats bark high-pitched yips to navigate the dark night sky by echolocation. But a new study reveals that as they fly, those cries often drop to a whisper, or even silence, suggesting the bats may steer themselves through the darkness with some of the quietest sonar on record. To find out how hoary bats navigate, researchers used infrared cameras and ultrasonic microphones to record scores of them flying through a riverside corridor in California on five autumn nights. In about half of the nearly 80 flights, scientists captured a novel type of call. Shorter, faster, and quieter than their usual calls, the new “micro” calls use three orders of magnitude less sound energy than other bats’ yaps did, the researchers report today in the Proceedings of the Royal Society B. As bats approached objects, they would often quickly increase the volume of their calls. But in close to half the flights, researchers did not pick up any calls at all. This stealth flying mode may explain one sad fact of hoary bat life: They suffer more fatal run-ins with wind turbines than other bat species in North America. The microcalls are so quiet that they reduce the distance over which bats can detect large and small objects by more than three times. That also cuts bats’ reaction time by two-thirds, making them too slow to catch their insect prey. © 2018 American Association for the Advancement of Science

Keyword: Hearing
Link ID: 24928 - Posted: 05.02.2018

Helen Thompson In the pitch-black waters beneath the Arctic ice, bowhead whales get funky. A small population of endangered bowheads belt an unusually varied repertoire of songs, which grows more diverse during mating season. Hunted to near extinction in the 1600s, these fire truck–sized mammals now number in the 300s in the frigid waters around the Svalbard archipelago in Norway. Underwater audio recorders captured the whales singing 184 acoustically distinct songs from October to April in 2010 through 2014. On the bowhead charts, a song's popularity is fleeting. Most recorded songs were heard for less than 100 hours total, although one song registered over 730 hours total. Some songs appeared in more than one month, but none repeated annually. December and January, likely the height of breeding season, saw a wider array of new bowhead songs than other months, researchers report in the April Biology Letters. Hearing a more distinct mixtape may play a role in enticing a female to mate. A hot cetacean band The Spitzbergen bowhead whale songbook contains a wide variety of tunes, and some stick around on the charts longer than others. Here each bubble corresponds to one of the 184 songs recorded by researchers from 2010 to 2014. The size of the bubble corresponds to the number of hours it was sung. Click on any of the dark green bubbles to hear that whale’s song. Groups of humpback whales don't change their tunes much in a given year, compared with bowheads. Only a few songbird species boast similar diversity. © Society for Science & the Public 2000 - 2018.

Keyword: Animal Communication; Sexual Behavior
Link ID: 24927 - Posted: 05.01.2018

By Abby Olena At both three and nine weeks after guinea pigs’ cochleae were treated with nanoparticles loaded with Hes1 siRNA, the authors observed what are likely immature hair cells. MODIFIED FROM X. DU ET AL., MOLECULAR THERAPY, 2018Loud sounds, infections, toxins, and aging can all cause hearing loss by damaging so-called hair cells in the cochlea of the inner ear. In a study published today (April 18) in Molecular Therapy, researchers stimulated hair cell renewal with small interfering RNAs (siRNAs) delivered via nanoparticles to the cochlea of adult guinea pigs, restoring some of the animals’ hearing. “There are millions of people suffering from deafness” caused by hair cell loss, says Zheng-Yi Chen, who studies hair cell regeneration at Harvard University and was not involved in the work. “If you can regenerate hair cells, then we really have potential to target treatment for those patients.” Some vertebrates—chickens and zebrafish, for instance—regenerate their hair cells after damage. Hair cells of mammals, on the other hand, don’t sprout anew after being damaged, explaining why injuries can cause life-long hearing impairments. Recent research suggests that there might be a workaround, by manipulating signaling pathways that can lead to hair cell differentiation. That’s where Richard Kopke comes in. © 1986-2018 The Scientist

Keyword: Hearing
Link ID: 24908 - Posted: 04.27.2018

By Jeremy Rehm Whales can sing, buzz, and even whisper to one another, but one thing has remained unknown about these gregarious giants: how they hear. Given the size of some whales and their ocean home, studying even the basics of these mammals has proved challenging. But two researchers have now developed a way to determine how baleen whales such as humpbacks hear their low-frequency (10- to 200-hertz) chatter, and they found some bone-rattling results. Baleen whales have a maze of ear bones that fuse to their skull, leading scientists to suppose the skull helps whales hear. Under this premise, the researchers used a computerized tomography scanner meant for rockets to scan the preserved bodies of a minke whale calf (Balaenoptera acutorostrata) and a fin whale calf (B. physalus), both of which had stranded themselves along U.S. coasts years before and died during rescue operations. Their preserved bodies were kept as scientific specimens. The researchers used these body scans (an example of which is displayed above) to produce 3D computer models to study how the skull responded to different sound frequencies. The skull acts like an antenna, the scientists reported today in San Diego, California, at the 2018 Experimental Biology conference, vibrating as sound waves impact it and then transmitting those vibrations to the whale’s ears. For ease of viewing, the scientists amplified the vibrations 20,000 times. Whale skulls were especially sensitive to the low-frequency sounds they speak with, the researchers found, but large shipping vessels also produce these frequencies. This new information could now help large-scale shipping industries and policymakers establish regulations to minimize the effects of humanmade noise on these ocean giants. © 2018 American Association for the Advancement of Science

Keyword: Hearing
Link ID: 24891 - Posted: 04.24.2018

Jon Hamilton The words "dog" and "fog" sound pretty similar. Yet even a preschooler knows whether you're talking about a puppy or the weather. Now scientists at Georgetown University Medical Center in Washington, D.C., have identified a two-step process that helps our brains learn to first recognize, then categorize new sounds even when the differences are subtle. And it turns out the process is very similar to the way the human brain categorizes visual information, the Georgetown team reports Wednesday in the journal Neuron. "That's very exciting because it suggests there are general principles at work here of how the brain makes sense of the world," says Maximilian Riesenhuber, an author of the study and a professor in Georgetown University School of Medicine's Department of Neuroscience. The finding also could help explain what goes wrong in disorders like dyslexia, which can impair the brain's ability to make sense of what it sees and hears, Riesenhuber says. The research began as an effort to understand how the brain is able to accomplish feats like recognizing a familiar word, even when it's spoken with an accent or unusual pronunciation. "You hear my voice," says Riesenhuber, who has a slight German accent. "You've probably never heard me before. But you can hopefully recognize what I'm saying." © 2018 npr

Keyword: Animal Communication; Hearing
Link ID: 24882 - Posted: 04.19.2018

Joan McFadden When Les Milne was diagnosed with Parkinson’s disease aged just 45, his wife Joy was, understandably, devastated. But her sadness wasn’t just down to the fact her husband was in the grip of such a terrible illness but that, when she’d noticed a change in his smell 12 years earlier, she hadn’t realised the two things might be connected. Upon first noticing a “sort of woody, musky odour” Joy “started suggesting tactfully to him that he wasn’t showering enough or cleaning his teeth,” she recalls. “He clearly didn’t smell it and was quite adamant that he was washing properly.” Joy, a former nurse, let the issue lie, occupied with the far more pressing issue of her husband’s rapidly changing character. “He wasn’t the man I’d known since I was 16. About eight years before he was diagnosed he started suffering from mood swings, with bursts of anger which left me dreading what might come next.” When Les was eventually referred for a brain scan, he was told that his symptoms indicated a diagnosis of either a brain tumour or Parkinson’s, which affects one in 500 people in the UK. As medical professionals - Les worked as an anaesthetist - both knew just how serious the diagnosis was, though Joy admits that it was a relief to have one at all. Forced to retire five years later, the pair moved back to Perth from Cheshire, with his growing inability to sleep and diminishing motor skills seeing Les, a former water polo player for Scotland, give up the swimming he loved to do every day. “He was just a completely different person. It was devastating to watch" Joy, now 67, says. © Telegraph Media Group Limited 2018

Keyword: Chemical Senses (Smell & Taste); Parkinsons
Link ID: 24828 - Posted: 04.06.2018

Rachel Ehrenberg BOSTON — Getting your groove on solo with headphones on might be your jam, but it can’t compare with a live concert. Just ask your brain. When people watch live music together, their brains waves synchronize, and this brain bonding is linked with having a better time. The new findings, reported March 27 at a Cognitive Neuroscience Society meeting, are a reminder that humans are social creatures. In western cultures, performing music is generally reserved for the tunefully talented, but this hasn’t been true through much of human history. “Music is typically linked with ritual and in most cultures is associated with dance,” said neuroscientist Jessica Grahn of Western University in London, Canada. “It’s a way to have social participation.” Study participants were split into groups of 20 and experienced music in one of three ways. Some watched a live concert with a large audience, some watched a recording of the concert with a large audience, and some watched the recording with only a few other people. Each person wore EEG caps, headwear covered with electrodes that measure the collective behavior of the brain’s nerve cells. The musicians played an original song they wrote for the study. The delta brain waves of audience members who watched the music live were more synchronized than those of people in the other two groups. Delta brain waves fall in a frequency range that roughly corresponds to the beat of the music, suggesting that beat drives the synchronicity, neuroscientist Molly Henry, a member of Grahn’s lab, reported. The more synchronized a particular audience member was with others, the more he or she reported feeling connected to the performers and enjoying the show. |© Society for Science & the Public 2000 - 2018

Keyword: Hearing
Link ID: 24800 - Posted: 03.30.2018

Aimee Cunningham As mice plumped up on a high-fat diet, some of their taste buds vanished. This disappearing act could explain why some people with obesity seem to have a weakened sense of taste, which may compel them to eat more. Compared with siblings that were fed normal mouse chow, mice given high-fat meals lost about 25 percent of their taste buds over eight weeks. Buds went missing because mature taste bud cells died off more quickly, and fewer new cells developed to take their place. Chronic, low-level inflammation associated with obesity appears to be behind the loss, researchers report March 20 in PLOS Biology. Taste buds, each a collection of 50 to 100 cells, sense whether a food is sweet, sour, bitter, salty or umami (savory). These cells help identify safe and nourishing food, and stimulate reward centers in the brain. The tongue’s taste bud population is renewed regularly; each bud lasts about 10 days. Special cells called progenitor cells give rise to new taste bud cells that replace old ones. Some studies have suggested that taste becomes duller in people with obesity, although why that is has remained unclear. But if taste becomes less intense, “then maybe you don’t get the positive feeling that you should,” which could give way to more overeating, says study coauthor Robin Dando, who studies the biology of taste at Cornell University. Nearly 40 percent of U.S. adults have obesity, determined by a person’s body mass index, a ratio of weight to height. The condition is linked to a number of health problems, including heart disease, diabetes and cancer. |© Society for Science & the Public 2000 - 2018

Keyword: Obesity; Chemical Senses (Smell & Taste)
Link ID: 24777 - Posted: 03.21.2018

By VERONIQUE GREENWOOD Ears are a peculiarly individual piece of anatomy. Those little fleshy seashells, whether they stick out or hang low, can be instantly recognizable in family portraits. And they aren’t just for show. Researchers have discovered that filling in an external part of the ear with a small piece of silicone drastically changes people’s ability to tell whether a sound came from above or below. But given time, the scientists show in a paper published Monday in the Journal of Neuroscience, the brain adjusts to the new shape, regaining the ability to pinpoint sounds with almost the same accuracy as before. Scientists already knew that our ability to tell where a sound is coming from arises in part from sound waves arriving at our ears at slightly different times. If a missing cellphone rings from the couch cushions to your right, the sound reaches your right ear first and your left ear slightly later. Then, your brain tells you where to look. But working out whether a sound is emanating from high up on a bookshelf or under the coffee table is not dependent on when the sound reaches your ears. Instead, said Régis Trapeau, a neuroscientist at the University of Montreal and author of the new paper, the determination involves the way the sound waves bounce off outer parts of your ear. Curious to see how the brain processed this information, the researchers set up a series of experiments using a dome of speakers, ear molds made of silicone and an fMRI machine to record brain activity. Before being fitted with the pieces of silicone, volunteers heard a number of sounds played around them and indicated where they thought the noises were coming from. In the next session, the same participants listened to the same sounds with the ear molds in. This time it was clear that something was very different. © 2018 The New York Times Company

Keyword: Hearing
Link ID: 24727 - Posted: 03.07.2018

By DOUGLAS QUENQUA Claudio Mello was conducting research in Brazil’s Atlantic Forest about 20 years ago when he heard a curious sound. It was high-pitched and reedy, like a pin scratching metal. A cricket? A tree frog? No, a hummingbird. At least that’s what Dr. Mello, a behavioral neuroscientist at Oregon Health and Science University, concluded at the time. Despite extensive deforestation, the Atlantic Forest is one of Earth’s great cradles of biological diversity. It is home to about 2,200 species of animals, including about 40 species of hummingbirds. The variety of hummingbirds makes it difficult to isolate specific noises without sophisticated listening or recording devices. In 2015, Dr. Mello returned to the forest with microphones used to record high-frequency bat noises. The recordings he made confirmed that the calls were coming from black jacobin hummingbirds. The species is found in other parts of South America, too, and researchers are unsure whether the sound is emitted by males, females or both, although they have confirmed that juvenile black jacobins do not make them. When Dr. Mello and his team analyzed the noise — a triplet of syllables produced in rapid succession — they discovered it was well above the normal hearing range of birds. Peak hearing sensitivity for most birds is believed to rest between two to three kilohertz. (Humans are most sensitive to noises between one and four kilohertz.) “No one has ever described that a bird can hear even above 8, 9 kilohertz,” said Dr. Mello. But “the fundamental frequency of those calls was above 10 kilohertz,” he said. “That’s what was really amazing.” © 2018 The New York Times Company

Keyword: Hearing; Animal Communication
Link ID: 24725 - Posted: 03.06.2018

By Virginia Morell A dog searching for a lost child is typically given an item of clothing to smell. But what does that scent “look” like? To find out, scientists tested 48 dogs, half of which had special police or rescue training. In a laboratory room, the scientists slid each dog’s favorite toy across the floor to a hiding place, while the dog waited in another room. One researcher then brought the dog to the testing room and pointed at the starting point of the odor trail and told the dog, “Look for it! Bring it!” In one trial, the dog found either its favored toy or—surprise!—a different item. Many of the surprised dogs continued searching for the toy used to lay the scent trail—an indication that they had a mental representation of what they expected to find, the scientists report today in the Journal of Comparative Psychology. Both family dogs and working dogs scored about the same on the tests, confirming previous studies showing that education doesn’t necessarily improve a dog’s performance. Previous studies have shown that horses have mental images of their owners and other horses—based on the sounds of their voices and whinnies. But scientists know little about how smell and cognition are linked in animals that rely heavily on smell—such as dogs, elephants, and rats. Now, we have a better idea at least for our pooches: They picture what they’re searching for. © 2018 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 24722 - Posted: 03.06.2018