Links for Keyword: Hearing

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by Jacob Aron The mystery of how our brains perceive sound has deepened, now that musicians have smashed a limit on sound perception imposed by a famous algorithm. On the upside this means it should be possible to improve upon today's gold-standard methods for audio perception. Devised over 200 years ago, the Fourier transform is a mathematical process that splits a sound wave into its individual frequencies. It is the most common method for digitising analogue signals and some had thought that brains make use of the same algorithm when turning the cacophony of noise around us into individual sounds and voices. To investigate, Jacob Oppenheim and Marcelo Magnasco of Rockefeller University in New York turned to the Gabor limit, a part of the Fourier transform's mathematics that makes the determination of pitch and timing a trade-off. Rather like the uncertainty principle of quantum mechanics, the Gabor limit states you can't accurately determine a sound's frequency and its duration at the same time. 13 times better The pair reasoned that if people's hearing obeyed the Gabor limit, this would be a sign that they were using the Fourier transform. But when 12 musicians, some instrumentalists, some conductors, took a series of tests, such as judging slight changes in the pitch and duration of sounds at the same time, they beat the limit by up to a factor of 13. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17775 - Posted: 02.09.2013

By C. CLAIBORNE RAY Q. Nearing 70, I have increasing difficulty hearing conversations, yet music in restaurants is too loud. Why? A. Age-related hearing loss, called presbycusis, is characterized by loss of hair cells in the base of the cochlea, or inner ear, that are attuned to capture and transmit high-frequency sounds, said Dr. Anil K. Lalwani, director of otology, neurotology and skull-base surgery at NewYork-Presbyterian Hospital/Columbia University Medical Center. Loss of high-frequency hearing leads to deterioration in the ability to distinguish words in conversation. Additionally, any noise in the environment leads to even greater loss in clarity of hearing. “Contrary to expectation, presbycusis is also associated with sensitivity to loud noises,” Dr. Lalwani said. “This is due to a poorly understood phenomenon called recruitment.” Normally, a specific sound frequency activates a specific population of hair cells located at a specific position within the cochlea. With hearing loss, this specificity is lost, and a much larger population of hair cells in the adjacent areas is “recruited” and also activated, producing sensitivity to noise. “Patients with presbycusis perceive an incremental increase in loudness to be much greater than those with normal hearing,” he said. “This explains why the elderly parent complains that ‘I am not deaf!’ ” when a son or daughter repeats a misheard sentence. © 2013 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 13: Memory, Learning, and Development
Link ID: 17760 - Posted: 02.05.2013

By James Gallagher Health and science reporter, BBC News A tiny "genetic patch" can be used to prevent a form of deafness which runs in families, according to animal tests. Patients with Usher syndrome have defective sections of their genetic code which cause problems with hearing, sight and balance. A study, published in the journal Nature Medicine, showed the same defects could be corrected in mice to restore some hearing. Experts said it was an "encouraging" start. There are many types of Usher syndrome tied to different errors in a patient's DNA - the blueprint for building every component of the body. One of those mutations runs in families descended from French settlers in North America. When they try to build a protein called hormonin, which is needed to form the tiny hairs in the ear that detect sound, they do not finish the job. It results in hearing loss at birth and has a similar effect in the eye where it causes a gradual loss of vision. Scientists at the Rosalind Franklin University of Medicine and Science, in Chicago in the US, designed a small strip of genetic material which attaches to the mutation and keeps the body's factories building the protein. There has been something of a flurry of developments in restoring hearing in the past year. BBC © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17759 - Posted: 02.05.2013

by Elizabeth Devitt Birds may not have big brains, but they know how to navigate. They wing around town and across continents with amazing accuracy, while we watch and wonder. Biologists believe that sight, smell, and an internal compass all contribute to avian orienteering. But none of these skills completely explains how birds fly long distances or return home from places they've never been. A new study proposes that the animals use infrasound—low-level background noise in our atmosphere—to fly by "images" they hear. These acoustical maps may also explain how other creatures steer. Scientists have long considered infrasound as a navigational cue for birds. But until U.S. Geological Survey geophysicist Jonathan Hagstrum in Menlo Park, California, became intrigued by the unexplained loss of almost 60,000 pigeons during a race from France to England in 1997, no one pinpointed how the process worked. The race went bust when the birds' flight route crossed that of a Concorde jet, and Hagstrum wanted to know why. "When I realized the birds in that race were on the same flight path as the Concorde, I knew it had to be infrasound," he says. The supersonic plane laid down a sonic boom when most of the animals were flying across the English Channel. Normally, infrasound is generated when deep ocean waves send pressure waves reverberating into the land and atmosphere. Infrasound can come from other natural causes, such as earthquakes, or humanmade events, such as the acceleration of the Concorde. The long, slow waves move across vast distances. Although humans can't hear them, birds and other animals are able to tune in. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17746 - Posted: 02.02.2013

By Laura Sanders Older people with hearing loss may suffer faster rates of mental decline. People who have hearing trouble suffered meaningful impairments in memory, attention and learning about three years earlier than people with normal hearing, a study published online January 21 in JAMA Internal Medicine reveals. The finding bolsters the idea that hearing loss can have serious consequences for the brain, says Patricia Tun of Brandeis University in Waltham, Mass., who studies aging. “I’m hoping it will be a real wake-up call in terms of realizing the importance of hearing.” Compared with other senses, hearing is often overlooked, Tun says. “We are made to interact with language and to listen to each other, and it can have damaging effects if we don’t.” Frank Lin of Johns Hopkins School of Medicine and colleagues tested the hearing of 1,984 older adults. Most of the participants, who averaged 77 years old, showed some hearing loss — 1,162 volunteers had trouble hearing noises of less than 25 decibels, comparable to a whisper or rustling leaves. The volunteers’ deficits reflect the hearing loss in the general population: Over half of people older than 70 have trouble hearing. Over the next six years, these participants underwent mental evaluations that measured factors such as short-term memory, attention and the ability to quickly match numbers to symbols. Everybody got worse at the tasks as time wore on, but people with hearing loss had an especially sharp decline, the team found. On average, a substantial drop in performance would come about three years earlier to people with hearing loss. © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 13: Memory, Learning, and Development
Link ID: 17699 - Posted: 01.22.2013

by Jennifer Viegas The world’s largest archive of animal vocalizations and other nature sounds is now available online. This resource for students, filmmakers, scientists and curious wildlife aficionados took archivists a dozen years to assemble and make ready for the web. “In terms of speed and the breadth of material now accessible to anyone in the world, this is really revolutionary,” audio curator Greg Budney said in a press release, describing the milestone just achieved by the Macaulay Library archive at the Cornell Lab of Ornithology. “This is one of the greatest research and conservation resources at the Cornell Lab,” added Budney. “And through its digitization, we’ve swung the doors open on it in a way that wasn’t possible 10 or 20 years ago.” The collection goes way back to 1929. It contains nearly 150,000 digital audio recordings equaling more than 10 terabytes of data with a total run time of 7,513 hours. About 9,000 species are represented. Many are birds, but the collection also includes sounds of whales, elephants, frogs, primates and more. “Our audio collection is the largest and the oldest in the world,” explained Macaulay Library director Mike Webster. “Now, it’s also the most accessible. We’re working to improve search functions and create tools people can use to collect recordings and upload them directly to the archive. Our goal is to make the Macaulay Library as useful as possible for the broadest audience possible.” © 2013 Discovery Communications, LLC

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17697 - Posted: 01.19.2013

Search recordings by species: 135793 recordings found

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17696 - Posted: 01.19.2013

by Gretchen Vogel All you graying, half-deaf Def Leppard fans, listen up. A drug applied to the ears of mice deafened by noise can restore some hearing in the animals. By blocking a key protein, the drug allows sound-sensing cells that are damaged by noise to regrow. The treatment isn't anywhere near ready for use in humans, but the advance at least raises the prospect of restoring hearing to some deafened people. When it comes to hearing, hair cells in the inner ear, so named for their bristlelike appearance, keep the process humming along, converting mechanical vibrations caused by sound waves into nerve impulses. Unfortunately for people, loud noises can overwork and destroy the cells. And once they're gone, they're gone: Birds and fish can regenerate the inner ear hair cells, but mammals cannot. Researchers have been looking for ways to reactivate the regenerative potential that other species enjoy. In 2005, scientists used gene therapy to prompt the growth of hair cells in the inner ears of adult guinea pigs, which restored some hearing. However, the drug approach would potentially be much easier to use in the clinic, says Albert Edge, a stem cell biologist at the Massachusetts Eye and Ear Infirmary in Boston. He and his colleagues had previously found that a class of drugs called gamma-secretase inhibitors could prompt the growth of hair cells from inner ear stem cells growing in the lab. The lab also showed that the drugs worked by blocking the signaling of the Notch protein, which helps determine which cells become hair cells and which become support cells during ear development. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 13: Memory, Learning, and Development
Link ID: 17663 - Posted: 01.10.2013

By Diane Mapes The video touched millions: An 8-month old boy smiles with unabashed adoration at his mother as he hears her voice, seemingly for the first time, thanks to a new cochlear implant. Posted on YouTube in April of 2008, the video of "Jonathan's Cochlear Implant Activation" has received more than 3.6 million hits and thousands of comments from viewers, many clamoring for an update. Five-year-old Jonathan is “doing great,” according to his parents, Brigette and Mark Breaux of Houston, Texas. "He's in kindergarten and we're working on speech," Brigette, his 35-year-old stay-at-home mom, told TODAY.com. "He can hear everything that we say to him. It's of course artificial hearing but he can hear and understand what we're saying." After a bout with bacterial meningitis left him deaf, Jonathan Breaux regained hearing with the help of a cochlear implant, and is now a happy 5-year-old. "He's a flirt," adds Mark, a 36-year-old corporate controller. "He was chasing girls around the playground when Brigette went to see him for his class party. He's a handful." © 2013 NBCNews.com

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17656 - Posted: 01.07.2013

Julian Richards, deputy editor, newscientist.com Let's take it from the top again... Human singing stars these days rely on Auto-Tune technology to produce the right pitch, but this songbird does it the old way - by listening out for its own mistakes. And it's also smart enough to ignore notes that are too far off to be true. Brains monitor their owners' physical actions via the senses, and use this feedback to correct mistakes in those actions. Many models of learning assume that the bigger the perceived mistake, the bigger the correction will be. Samuel Sober at Emory University in Atlanta, Georgia, and Michael Brainard of the University of California, San Francisco, suspected that the system is a bit cleverer than that - otherwise, for instance, a bird might over-correct its singing if it confused external sounds with its own voice, or if its brain made a mistake in processing sounds. They decided to fool Bengalese finches into thinking that they were singing out of tune, and measured what happened at different levels of this apparent tone-deafness. To do this, they fitted the birds with the stylish headphones shown in the photo above and fed them back the sound of their own singing, processed to sound sharper than it really was. The researchers sharpened the birdsong by degrees ranging from a quarter-tone to one-and-a-half tones. They found that the birds learned to "correct" their pitch more accurately and more quickly when they heard a smaller mistake than when they heard a large one. It was also clear that the bird brains took "errors" seriously when they fell within the normal range of pitches in the bird's song: the birds seemed to ignore errors outside this range. © Copyright Reed Business Information Ltd

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 13: Memory, Learning, and Development
Link ID: 17627 - Posted: 12.22.2012

By Wynne Parry and LiveScience NEW YORK — While jazz musician Vijay Iyer played a piece on the piano, he wore an expression of intense concentration. Afterward, everyone wanted to know: What was going on in his head? The way this music is often taught, "they tell you, you must not be thinking when you are playing," Iyer said after finishing his performance of John Coltrane's "Giant Steps," a piece that requires improvisation. "I think that is an impoverished view of what thought is. … Thought is distributed through all of our actions." Iyer's performance opened a panel discussion on music and the mind at the New York Academy of Sciences on Wednesday (Dec. 13). Music elicits "a splash" of activity in many parts of the brain, said panelist Jamshed Bharucha, a neuroscientist and musician, after moderator Steve Paulson of the public radio program "To the Best of Our Knowledge" asked about the brain's response to music. "I think you are asking a question we can only scratch the surface of in terms of what goes on in the brain," Bharucha said. [Why Music Moves Us] Creativity in the brain scanner Charles Limb, a surgeon who studies the neuroscience of music, is attempting to better understand creativity by putting jazz musicians and rappers in a brain-imaging scanner called a functional MRI, which measures blood flow in the brain, and asking them to create music or rap once in there. © 2012 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 17618 - Posted: 12.19.2012

By DOUGLAS MARTIN Dr. William F. House, a medical researcher who braved skepticism to invent the cochlear implant, an electronic device considered to be the first to restore a human sense, died on Dec. 7 at his home in Aurora, Ore. He was 89. The cause was metastatic melanoma, his daughter, Karen House, said. Dr. House pushed against conventional thinking throughout his career. Over the objections of some, he introduced the surgical microscope to ear surgery. Tackling a form of vertigo that doctors had believed was psychosomatic, he developed a surgical procedure that enabled the first American in space to travel to the moon. Peering at the bones of the inner ear, he found enrapturing beauty. Even after his ear-implant device had largely been supplanted by more sophisticated, and more expensive, devices, Dr. House remained convinced of his own version’s utility and advocated that it be used to help the world’s poor. Today, more than 200,000 people in the world have inner-ear implants, a third of them in the United States. A majority of young deaf children receive them, and most people with the implants learn to understand speech with no visual help. Hearing aids amplify sound to help the hearing-impaired. But many deaf people cannot hear at all because sound cannot be transmitted to their brains, however much it is amplified. This is because the delicate hair cells that line the cochlea, the liquid-filled spiral cavity of the inner ear, are damaged. When healthy, these hairs — more than 15,000 altogether — translate mechanical vibrations produced by sound into electrical signals and deliver them to the auditory nerve. Dr. House’s cochlear implant electronically translated sound into mechanical vibrations. His initial device, implanted in 1961, was eventually rejected by the body. But after refining its materials, he created a long-lasting version and implanted it in 1969. © 2012 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17610 - Posted: 12.17.2012

By WILLIAM J. BROAD When a hurricane forced the Nautilus to dive in Jules Verne’s “Twenty Thousand Leagues Under the Sea,” Captain Nemo took the submarine down to a depth of 25 fathoms, or 150 feet. There, to the amazement of the novel’s protagonist, Prof. Pierre Aronnax, no whisper of the howling turmoil could be heard. “What quiet, what silence, what peace!” he exclaimed. That was 1870. Today — to the dismay of whale lovers and friends of marine mammals, if not divers and submarine captains — the ocean depths have become a noisy place. The causes are human: the sonar blasts of military exercises, the booms from air guns used in oil and gas exploration, and the whine from fleets of commercial ships that relentlessly crisscross the global seas. Nature has its own undersea noises. But the new ones are loud and ubiquitous. Marine experts say the rising clamor is particularly dangerous to whales, which depend on their acute hearing to locate food and one another. To fight the din, the federal government is completing the first phase of what could become one of the world’s largest efforts to curb the noise pollution and return the sprawling ecosystem to a quieter state. The project, by the National Oceanic and Atmospheric Administration, seeks to document human-made noises in the ocean and transform the results into the world’s first large sound maps. The ocean visualizations use bright colors to symbolize the sounds radiating out through the oceanic depths, frequently over distances of hundreds of miles. © 2012 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17589 - Posted: 12.11.2012

Alla Katsnelson Human eyes, set as they are in front-facing sockets, give us a limited angle of view: we see what is directly in front of us, with only a few degrees of peripheral vision. But bats can broaden and narrow their 'visual field' by modulating the frequency of the squeaks they use to navigate and find prey, researchers in Denmark suggest today in Nature1. Bats find their way through the night by emitting sonar signals and using the echoes that return to them to create a map of their surroundings — a process called echolocation. Researchers have long known that small bats emit higher-frequency squeaks than larger bats, and most assumed that the difference arises because the smaller animals must catch smaller insects, from which low-frequency sound waves with long wavelengths do not reflect well. That didn't sound right to Annemarie Surlykke, a neurobiologist who studies bat echolocation at the University of Southern Denmark in Odense. “When you look at the actual frequencies, small bats would be able to detect even the smallest prey they take with a much lower frequency,” she says. “So there must be another reason.” Surlykke and her colleagues decided to test the hypothesis by studying six related species of bat that varied in size. They captured the animals in the wild and set them loose in a flight room — a pitch-dark netted corridor 2.5 metres high, 4.8 metres wide and 7 metres long, rigged on all sides with microphones and infrared cameras. “It’s a pretty confined space, so this corresponds to flying close to vegetation,” says Surlykke. © 2012 Nature Publishing Group

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17536 - Posted: 11.26.2012

by Douglas Heaven All the better to hear you with, my dear. A chance discovery has revealed that some insects have evolved mammal-like ears, with an analogous three-part structure that includes a fluid-filled vessel similar to the mammalian cochlea. Fernando Montealegre-Z at the University of Lincoln, UK, and colleagues were studying the vibration of the tympanal membrane – a taut membrane that works like an eardrum – in the foreleg of Copiphora gorgonensis, a species of katydid from the South American rainforest, when they noticed tiny vibrations in the rigid cuticle behind the membrane. When they dissected the leg behind that membrane, they unexpectedly burst a vessel filled with high-pressure fluid. The team analysed the fluid to confirm that it was not part of the insect's circulatory system and concluded instead that it played a cochlea-like role in sound detection. In most insects, sound vibrations transmit directly to neuronal sensors which sit behind the tympanal membrane. Mammals have evolved tiny bones called ossicles that transfer vibrations from the eardrum to the fluid-filled cochlea. The analogous structure in the katydid is a vibrating plate, exposed to the air on one side and fluid on the other. Smallest ear In mammals, the cochlea analyses a sound's frequency – how high or low it is – and the new structure found by the team appears to do the same job. Spanning only 600 micrometres, it is the smallest known ear of its kind in nature. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17497 - Posted: 11.17.2012

by Elizabeth Norton Stop that noise! Many creatures, such as human babies, chimpanzees, and chicks, react negatively to dissonance—harsh, unstable, grating sounds. Since the days of the ancient Greeks, scientists have wondered why the ear prefers harmony. Now, scientists suggest that the reason may go deeper than an aversion to the way clashing notes abrade auditory nerves; instead, it may lie in the very structure of the ear and brain, which are designed to respond to the elegantly spaced structure of a harmonious sound. "Over the past century, researchers have tried to relate the perception of dissonance to the underlying acoustics of the signals," says psychoacoustician Marion Cousineau of the University of Montreal in Canada. In a musical chord, for example, several notes combine to produce a sound wave containing all of the individual frequencies of each tone. Specifically, the wave contains the base, or "fundamental," frequency for each note plus multiples of that frequency known as harmonics. Upon reaching the ear, these frequencies are carried by the auditory nerve to the brain. If the chord is harmonic, or "consonant," the notes are spaced neatly enough so that the individual fibers of the auditory nerve carry specific frequencies to the brain. By perceiving both the parts and the harmonious whole, the brain responds to what scientists call harmonicity. In a dissonant chord, however, some of the notes and their harmonics are so close together that two notes will stimulate the same set of auditory nerve fibers. This clash gives the sound a rough quality known as beating, in which the almost-equal frequencies interfere to create a warbling sound. Most researchers thought that phenomenon accounted for the unpleasantness of a dissonance. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17486 - Posted: 11.13.2012

by Will Ferguson For the first time, an electrical device has been powered by the ear alone. The team behind the technology used a natural electrochemical gradient in cells within the inner ear of a guinea pig to power a wireless transmitter for up to five hours. The technique could one day provide an autonomous power source for brain and cochlear implants, says Tina Stankovic, an auditory neuroscientist at Harvard University Medical School in Boston, Massachusetts. Nerve cells use the movement of positively charged sodium ions and negatively charged potassium ions across a membrane to create an electrochemical gradient that drives neural signals. Some cells in the cochlear have the same kind of gradient, which is used to convert the mechanical force of the vibrating eardrum into electrical signals that the brain can understand. Tiny voltage A major challenge in tapping such electrical potential is that the voltage created is tiny – a fraction of that generated by a standard AA battery. "We have known about DC potential in the human ear for 60 years but no one has attempted to harness it," Stankovic says. Now, Stankovic and her colleagues have developed an electronic chip containing several tiny, low resistance electrodes that can harness a small amount of this electrical activity without damaging hearing. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17471 - Posted: 11.10.2012

When you hear the sound of a nail scratching a blackboard, the emotional and auditory part of your brain are interacting with one another, a new study reveals. The heightened activity and interaction between the amygdala, which is active in processing negative emotions, and the auditory parts of the brain explain why some sounds are so unpleasant to hear, scientists at Newcastle University have found. "It appears there is something very primitive kicking in," said Dr. Sukhbinder Kumar, the paper’s author. "It’s a possible distress signal from the amygdala to the auditory cortex." Researchers at the Wellcome Trust Centre for Neuroimaging at UCL and Newcastle University used functional magnetic resonance imaging (fMRI) to examine how the brains of 13 volunteers responded to a range of sounds. Listening to the noises inside the scanner, the volunteers rated them from the most unpleasant, like the sound of knife on a bottle, to the most pleasing, like bubbling water. Researchers were then able to study the brain response to each type of sound. "At the end of every sound, the volunteers told us by pressing a button how unpleasant they thought the sound was," Dr. Kumar said. Researchers found that the activity of the amygdala and the auditory cortex were directly proportional to the ratings of perceived unpleasantness. They concluded that the emotional part of the brain, the amygdala, in effect takes charge and modulates the activity of the auditory part of the brain, provoking our negative reaction. © CBC 2012

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 17364 - Posted: 10.13.2012

By Jason G. Goldman My high school biology teacher once told me that nothing was binary in biology except for alive and dead, and pregnant and not pregnant. Any other variation, he said, existed along a continuum. Whether or not the claim is technically accurate, it serves to illustrate an important feature of biological life. That is, very little in the biological world falls neatly into categories. A new finding, published today in PLoS ONE by Gustavo Arriaga, Eric P. Zhou, and Erich D. Jarvis from Duke University adds to the list of phenomena that scientists once thought were categorical but may, in fact, not be. The consensus among researchers was that, in general, animals divide neatly into two categories: singers and non-singers. The singers include songbirds, parrots, hummingbirds, humans, dolphins, whales, bats, elephants, sea lions and seals. What these species all have in common – and what distinguishes them from the non-singers of the animal world – is that they are vocal learners. That is, these species can change the composition of their sounds that emanate from the larynx (for mammals) or syrinx (for birds), both in terms of the acoustic qualities such as pitch, and in terms of syntax (the particular ordering of the parts of the song). It is perhaps not surprising that songbirds and parrots have been extremely useful as models for understanding human speech and language acquisition. When other animals, such as monkeys or non-human apes, produce vocalizations, they are always innate, usually reflexive, and never learned. But is the vocal learner/non-learner dichotomy truly reflective of biological reality? Maybe not. It turns out that mice make things more complicated. © 2012 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 17352 - Posted: 10.11.2012

by Sarah C. P. Williams Scientists have enabled deaf gerbils to hear again—with the help of transplanted cells that develop into nerves that can transmit auditory information from the ears to the brain. The advance, reported today in Nature, could be the basis for a therapy to treat various kinds of hearing loss In humans, deafness is most often caused by damage to inner ear hair cells—so named because they sport hairlike cilia that bend when they encounter vibrations from sound waves—or by damage to the neurons that transmit that information to the brain. When the hair cells are damaged, those associated spiral ganglion neurons often begin to degenerate from lack of use. Implants can work in place of the hair cells, but if the sensory neurons are damaged, hearing is still limited. "Obviously the ultimate aim is to replace both cell types," says Marcelo Rivolta of the University of Sheffield in the United Kingdom, who led the new work. "But we already have cochlear implants to replace hair cells, so we decided the first priority was to start by targeting the neurons." In the past, scientists have tried to isolate so-called auditory stem cells from embryoid bodie—aggregates of stem cells that have begun to differentiate into different types. But such stem cells can only divide about 25 times, making it impossible to produce them in the quantity needed for a neuron transplant. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 13: Memory, Learning, and Development
Link ID: 17252 - Posted: 09.13.2012