Posted by Liz Ernst on Mon, May 28, 2012 @ 10:22 PM
If you work in a cubicle-based office, these findings may or may not surprise you:
Originally designed to save space and foster communication between co-workers and management, the open-plan office has backfired for many, providing too much communication and too little privacy. With so many offices having adopted cubicle layouts worldwide, many staffers are finding ways to escape their noisy co-workers: headphones, barricades consisting of file cabinets and piles of folders, books and even boxes.
Social scientists have been studying the cubicle’s contribution to productivity – or lack thereof – and are discovering more than they had bargained for. Researchers at the University of California, Berkley surveyed more than 65,000 workers in North America, Australia, Africa and Europe who work in cubicle-style offices, and found that more than half complain of lack of “speech privacy” – which is the number one complaint among office workers everywhere.
There is a whole cubicle culture that has festered in workplaces for decades, making workers miserable, unable to focus, and not as productive as they could be due to the constant noisy distractions and interruptions. Companies are finally beginning to pay attention to the noise problem and its affect on the bottom line. Offices are being redesigned, sound abatement material is being installed in cubicles, interior office designers are incorporating soundproofing material in new cubicle wall designs, and acoustical engineers are being called upon to help right the wrongs.
“Sound masking” has become a particular focus for some managers, determined to address volume issues without losing the cubicle setups altogether.
An evolving technology etiquette is becoming the norm in many cubicle-style offices as well, and staff are wearing headphones to block out noise and distractions. Headphones are the new wall, according to one Manhattan office worker.
John Goins, who lead the survey team underwritten by Berkley’s Center for the Build Environment, says that with few exceptions – those being the workers who are the noisemakers – most office workers are unhappy with cubicle life.
“Noise is the most serious problem in the open-plan office, and speech is the most disturbing type of sound because it is directly understood in the brain’s working memory,” said Berkley Acoustician Valtteri Hongisto, who discovered that workers are more satisfied and perform better at cognitive tasks when speech sounds were masked by a background noise of a gently burbling brook.
Many studies show that conversations are shorter and less detailed in open offices because the discomfort level of having their phone conversations overheard has many workers unwilling or unable to bring themselves to have meaningful dialogues over the phone. Trying to address privacy needs among office workers while maintaining the open concept for collaboration has become a cottage industry in itself.
In 2009, software company Autodesk moved into a an open-plan building in Waltham, Massachusetts and installed what is known as a “pink-noise” system, which gives off a soft “whooshing” sound over a speaker system that mimics the sound a ventilation system makes. However, Autodesk’s system is specially formulated to match the frequencies of human voices, as this is how a dedicated sound masking systems works.
Still, despite the complaints worldwide about the open-plan and cubicle office designs, there are no plans to eliminate either because they are inexpensive and because the open floor design promotes communication. Certain workplaces, such as newsrooms and trading floors, depend on the open floor concept because informal collaboration is a critical element in these environments.
Finally, researchers at Finland’s Institute of Occupational Health have been studying the distance conversations carry in an open design office, and then analysed the effect on those office workers who unwillingly overheard the conversations simply due to proximity. Their findings show a decline of five- to 10-percent in cognitive task performance that required short term memory efficiency (reading, writing, and other forms of creative work) among the unwilling listeners subjected to the conversations.
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Posted by Liz Ernst on Wed, May 23, 2012 @ 02:05 AM
You know that feeling, that deep seated anger and helplessness you feel when a boom car pulls up next to you at the 7-11? You’re just trying to put gas in the tank and get on with your day, when all of a sudden the pavement beneath your feet shakes, and your stereoceillia – you know, the bundle of fibers in the inner ear hair cell that mechanically responds to vibration – gets so stressed, you’re going to spend the rest of your life struggling with tinnitus just because you stopped for gas.
But the kids in the boom car are oblivious to your pain. Apparently, they’re enjoying the music at decibel levels that rival those expressed by a jet engine taking off in the parking lot next door. How can they even identify it as music, you ask? It could be the sounds of the End Times, or the first rumblings of a tsunami for all anyone knows. There is no deciphering anything musical, with the exception of that deep, sonic, rhythmic boom, boom, boom that tells you someone was concerned with a beat here.
If you’re not sure where this is going, I’m straying from my usual textbook style blog posts to vent about boom cars, and their menace to society and all things decent.
Don’t get me wrong, I love music, and I love mine loud -- louder than is probably safe for my hearing, but not so loud that I can’t hear it. I like to decipher the lyrics and separate the instrumentals, and I believe that if you’ve never listened to Ode to Joy at vibration-causing decibels, you’re missing a spiritual experience of epic proportions. But I digress.
I do this risky music listening business with headphones because I am a considerate human being who does not want to force my need for high volume on anyone else. It’s rude, and dismissive of their space. But my listening habits couldn’t begin to rival the decibel levels of a boom car.
I understand the need to feel great music pulsing through the nervous system, I grew up listening to my music Pete-Townshend-went-deaf-because-it-was-so-loud, loud. We played our music loud but we didn’t take it to ear the drum shattering levels of today’s boom cars – and we’re still going deaf!
It makes you wonder if this generation of youthful boom car riders are going to be getting cochlear implants at age 25 due to their recklessness.
An organization called Noise Free America believes that the U.S. needs to reestablish an office of noise abatement and control. Noise free America believes that noise pollution has reached epidemic proportions, and we’re all going to go insane because of it.
Not really, I made that insane part up, but I do believe boom cars will drive 70 percent of the U.S. population insane, and that’s probably a scientifically provable figure.
The boom car industry is, well, booming and there seems to be no end in sight. Young people do not believe they will ever go deaf, and they don’t care if the rest of us do. Even more horrifying, their cars are integral to their 21st century version of a mating ritual. I can see the attraction – there can never be conversation, so no need for social skills, demonstrated brilliantly by the unwillingness of boom car owners and passengers to show an iota of consideration to anyone around them. So these couples are made for each other.
The boom car industry has also taken a terrible thing to new levels, in addition to promoting boom cars on the highway – you know, those same highways the rest of us travel? Creating an everyday hazard to society apparently isn’t enough. The boom car industry now underwrites national and international competitions that award those who can produce the loudest sound from their boom car. Wait, it gets even more incredible.
The boom car industry isn’t creating this monster alone – it has help from stereo companies that create the specialty stereo systems that blast music at outlandish decibels within the small space of a car! And it has help from an entire niche of auto body and electronics companies that build the cars and make them all shiny and pretty and irresistible to young, impressionable people who haven’t experienced the ravages of hearing loss yet, but who are desperate to pick up girls. It’s a lethal combination. And boom car owners, most of whom are about old enough to work minimum wage jobs if they’re not up all night trolling in their boom cars for girls, are spending thousands of dollars to get their boom cars ready for these competitions. Maybe they have excellent paper routes.
According to Noise Free America (NFA), these boom car competitions are called dB drag racing competitions, and they say that these contests are “not just ‘boys being boys’ or ‘good clean fun.’" Noise Free America says these competitions create death machines, due to the extreme intensity of sound and the ultra-low frequency levels produced.
Now this is really important – the extreme density of sound and the ultra low frequency levels produced – to sit in some of these boom cars during a sound competition, NFA says, would mean instant death.
“This type of vehicle is reinforced and highly modified to accommodate the massive amounts of amplifiers, sub-woofers, and electrical equipment,” the NFA report says.
The sound produced by some of these monsters is accomplished by remote control. More contestants than you want to know have blown whole ear drums in these competitions, and these are people who are still in their teens and early 20s. Unlike lizard tails, ear drums don’t grow back. Someone should explain this to them.
And, though some of these boom cars are not street worthy, young people who witness these competitions are inspired to go home and build their own boom car to drive on the street. Thus, even more of these hazards are on the road to menace and disrupt the peace and safety of society, and all that we know to be good and decent.
Boom car operators thrive on getting attention and being noticed. The more intense the decibels and the lower the frequency, the more respect and bragging rights they have over their peers - at least until the instant death part happens.
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Posted by Liz Ernst on Tue, May 22, 2012 @ 05:11 AM
Barking dogs – few people haven’t lost a night’s sleep, or at least spent an irritated afternoon listening to a neighbor’s dog bark incessantly.
When the barking of her neighbor’s German shepard awakened her at 4 a.m. morning after morning, Samantha Butler said she was at her wits end. The dog, Butler said, would often bark for hours at a time, and the owner did nothing to silence the animal.
Butler, a resident of East Orange, New Jersey filed a municipal complaint against her neighbors who now might face fines if their dog continues “barking, howling, crying,” or making any other bothersome noises for more than 30 minutes in an hour.
Butler had a sympathetic ear in City Council members who believe noise caused by a barking dog is a quality of life issue, and they're enforcing laws set in place to address the bothersome behavior.
East Orange is just one of at least 144 New Jersey municipalities with laws specifically addressing whining and barking dogs. In New York’s Nassau and Suffolk Counties, at least 30 towns have similar laws, and the trend is growing in Westchester County, Connecticut and other areas. Not only are lawmakers and city officials sympathetic to neighbors who are bothered by continual dog barking; many dog owners empathize with their neighbors, and want to alleviate the noise problem.
But some dogs just cannot be trained to be quiet.
As the pressure to be good neighbors and avoid fines mounts, dog owners are increasingly turning to a dramatic and permanent cure – surgical cutting of the dog’s vocal chords, also known as debarking. In some cities like New York, a barking dog can cost the pet owners their apartment if they refuse to get rid of the animal and the barking doesn’t cease. One New York veterinarian had his own pooch's vocal chords cut when a neighbour threatened to complain about the barking to the co-op board.
No reliable estimate exists that pinpoints how many dogs have their vocal cords cut annually, but animal experts and veterinarians say more and more dog owners are resorting to the measure. Drug dealers, who prefer their guard dogs to be silent, are also taking their animals in for the procedure.
The surgery, which leaves dogs with a wheeze or a squeak instead of a bark, has been in use for decades but is now frowned upon by younger veterinarians and animal rights advocates.
Keeping dogs in any close-living community has always required diplomacy and delicate negotiations between neighbors. But critics of debarking consider it an inhumane option because it destroys the animal's main means of communicating for the convenience of humans. More and more veterinarians are refusing to perform the procedure on ethical grounds, and those who do perform it don’t advertise the service for fear of repurcussions.
Like the UK and many other European cities, New Jersey bans debarking procedures except for medical intervention purposes, and other states are considering following suit.
But there are still those who advocate the procedure, and consider it to be a useful option for dog owners who love their pets and are facing serious consequences from the noise issues caused by their dog's barking.
The surgery is fairly simple, if done properly. The veterinarian anesthetizes the dog then cuts its vocal cords through the mouth, or through an incision in the larynx. Dogs generally recover quickly, according to veterinarians who perform the procedure. But others, like Dr. Gary Ellison of the College of Veterinary Medicine at the University of Florida, say it’s not that simple. Scar tissue can build up in the throats of debarked dogs, Ellison says, which can impede the dog’s breathing.
The American Veterinary Medical Association recommends that debarking surgery only be done “after behavioral modification efforts to correct excessive vocalization" and workable noise barriers that prevent the dog's barking from traveling into neighboring homes have failed.
People with debarked dogs say they are sensitive to animal rights groups’ concerns, but believe that they are being judged too harshly. For a pet owner faced with choosing between the debarking surgery and giving up their pet, there’s simply no choice.
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Posted by Liz Ernst on Tue, May 15, 2012 @ 12:14 AM
Even though most of us long for more peace and quiet in this noisy world, could it be that we’re not capable of making it happen?
This week, Virgin Airlines announced that it will make cell phone service available during flight time between London and New York. Also, the Economist reports that the so-called “quiet cars” or “quiet carriages” that have popped up on trains across the U.S. and Europe in recent years aren’t succeeding as planned.
Why can’t we all just pipe down for 30 minutes to eight hours of travel time? Planes have, until now, had a no-choice ban on cell phone use – even texting is forbidden once that aircraft door is closed and the pilot has turned on the fasten-seat-belt light, even if the aircraft has not begun taxiing. Ask Alec Baldwin – not even a friendly iPhone-based “Words for Friends” match will be tolerated.
If Virgin Airlines is about to start a trend that other airlines can’t afford to ignore, will we soon be trapped on a flight next to the cell-phone holler of a man talking to his hard-of-hearing mother? Or a teenager fighting with a boyfriend or girlfriend? Will it be less unpleasant if it’s just some person conducting business, while you find yourself re-reading page 109 of “Indignation” again and again because you can’t concentrate, because your seatmate is selling swivel couplings and hose retention systems at 33,000 feet?
Planes are noisy places to begin with. The roar of the aircraft’s engines drone continuously in the background, which many of us think we don’t hear, but we do. Babies crying, people talking, refreshment carts rattling – why not just throw cell phone talking onto the pile, amiright?
Let’s look at the “quiet carriages,” which began as such a great idea. People who needed to take a train to or from work, or just occasionally, can opt to ride in one of these quiet cars, where the rule is 'turn off your cell phone and keep your chattering to a minimum.' Voila! Peaceful trips every day for the stressed and cranky who just want some peace and quiet.
Trouble is, being quiet in these cars is voluntary, and not everyone who lands in a quiet car meant to. They ended up in the quiet car by accident, and had no intention of being quiet in the first place. And there are those who really want the quiet car, but find it impossible to ignore an important incoming call. So, there’s noise, even in the quiet car.
Some train operators are trying to figure out how to make being quiet in the quiet cars mandatory. Trains in Queensland, Australia, are having permanent signs added to show exactly what is expected; a British operator has invested in signal-jamming technology to prevent phone calls. Microeconomics suggests another approach: putting a price on noise.
Fining people for making noise would surely dissuade most, and in theory it’s a nifty solution, but in reality it’s a costly one that will require monitoring and enforcement. Another approach under consideration is to charge more for a ticket in the quiet car, which might confirm the passenger’s commitment to shutting up for the duration of the trip. Make it an optional extra when purchasing the ticket, and the passenger believes they are making a commitment to quiet when they pay the extra fare.
But the risk is that some passengers who pay the extra fare will find an unexpected excuse to breach the silence, and the blood pressure of the rest of the quiet car passengers will shoot up. Noise can be very unhealthy.
Still, some believe that charging a premium for quiet could solve the commitment problem. They’re also suggesting schemes that reward the zipper-lipped: a rating system among fellow passengers, for instance. The theory is similar to those people who pay for their purchases on Ebay in a timely fashion – they get stars and accolades, so everyone knows they’re a good Ebayer. But it isn’t clear how this would work for a quiet car rider, unless perhaps you can have the premium waived if you’re quiet for, say, 20 rides in a row and you can prove it because your fellow passengers motioned their approval. If losing your hard-won reputation as a courteous quiet person offsets the short-term gain from using the phone, well, it’s hard to say how many folks would value such a hard-won reputation.
Now, back to the cell phones on flights news. According to Virgin, cell phone service will cost the same as any other international roaming voice call, which can add up fast. At $1.29 or more per minute, price could be an effective deterrent to anything but the most critical calls for most flyers.
How do you feel about chatter and cell phone use on trains and planes? One more unpleasantry, or just another 55-75 decibels added to the din? Send us your thoughts.
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Posted by Liz Ernst on Fri, May 11, 2012 @ 02:27 PM
From the day they enter Kindergarden, children spend long stretches of time learning. Children develop their intellectual, social, and communication skills through their exposure to a variety of situations and experiences, and the classroom is central to the learning process for at least 12 years. The classroom experience is supposed to offer kids the stimuli and tools necessary to focus within a controlled environment, and eventually send them out into the world prepared to work, perhaps raise families, travel - whatever they choose to do with their proverbial oyster.
Now, consider the importance of the classroom environment to a child’s learning process. Researchers are finding that background noise and reverberation – much of which may not even be noticed by adults – adversely affects the learning environment of the classroom, particularly for younger children. Poor classroom acoustics add an extra burden to children with learning disabilities, speech impediments, and impaired hearing, even if the hearing impairment is temporary.
The harmful effect of noise on young children has been well documented. Apart from physiological hearing damage from prolonged exposure, a noisy environment can dull a child's listening skills. Just as frightening, children exposed to noisy surroundings routinely can lose the ability to distinguish some of the subtle speech components essential to the mastery of language. In today’s noisy world, many children have come to accept noise as a natural element in their everyday activities at home, in school or daycare, and in public places. The classroom should provide an environmental model that facilitates communication for all children regardless of their backgrounds or handicaps, and that requires acoustically optimized sourroundings.
Two important characteristics of an acoustically optimized classroom are a low background noise level and a low reverberation time. Classroom background noise may be caused by a heating/cooling ventilation (HVAC) unit, activity in an adjacent classroom or hallway, highway traffic or aircraft noise bleeding in from outside, student activity within the classroom, or any combination of these. Reverberation is the multiple reflections of sounds ricocheting off of hard surfaces within a room that can prolong and distort the original sound and interfere with speech intelligibility. It has the added effect of amplifying background noises, which compounds the problem.
A classroom with reverberant noise issues must be treated with sound absorbing material placed on top of the reflecting surfaces. Sound absorption also helps to reduce background noise levels and, by improving speech intelligibility, reduces the need for teachers to speak in raised voices in order to be heard by all pupils.
In Canada and Europe, workable classroom noise abatement policies have been in place for years, and the use of noise abatement materials is being implemented indoors, in addition to outdoor noise barrier fencing and structures to protect the hearing of both children and teachers.
Many older concrete structured schools are the worst classroom noise offenders, and a variety of corrective noise absorbing and noise barrier solutions are available that work easily with many of these old structures. Corrective action may also require the installation of reverberant noise absorping materials to the walls and ceilings too.
Obviously, a supportive acoustic environment is critical in any listening space, particularly the classroom where so much is at stake. Ideally, the acoustic quality of a classroom will enhance and project the teacher's voice, have a subdued level of reverberation or echo, and prevent the intrusion of unwanted sound, whether from the traffic outdoors, trains, airplanes, the building’s mechanical and HVAC systems and noise in adjacent spaces.
When you consider that approximately 60 percent of all classroom learning activities involve students listening to and participating in spoken communications with the teacher and other students, the presence of any serious, continuous noise should be a priority for corrective measures to be taken. Yet noise remains far too prevalent in American schools.
According to the United States General Accounting Office, millions of students attend schools with unsatisfactory acoustical conditions. 21,900 schools exhibit poor acoustics or noise control, affecting more than 11 million students. Twenty-eight percent of all U.S. schools report unsatisfactory or very unsatisfactory environmental noise conditions -- higher than ventilation (27 percent), physical security (24 percent), indoor air quality (19 percent), heating (18 percent), or lighting (16 percent).
The excessive noise levels and lack of support for speech in these classrooms have failed countless students and led to difficulties in learning and instruction. The impediment these classrooms pose to learning is often under-appreciated by students, teachers, and administrators. In some cases, problems caused by poor acoustic conditions may have been falsely attributed to other factors (teacher performance, socio-economic factors, etc). The poor listening conditions in American classrooms results from a lack of understanding and awareness of the detrimental impact that noise and reverberation have on student learning.
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Posted by Liz Ernst on Tue, May 08, 2012 @ 01:15 AM
If you’re old enough to have stepped foot in a hospital prior to, say, 1975, you remember it as a place of rest. Churches, libraries, and hospitals were once mandatory quiet zones, with signs plastered outside most American hospitals reminding passers-by to hush – there were, after all, people trying to heal inside.
Step inside any hospital today and you’re likely to experience noise hitting you from all angles; trays clattering, machines and gadgets beeping, buzzing, and blaring; doors opening and closing in varying degrees of loud, carts wheeling down concrete hallways, patients talking, visitors talking, nurses talking, physicians talking, physicians being paged...
Hospitals are still places of healing, but that doesn’t mean they’re restful.
For the past few years, American hospitals have been required to survey patients and report on 10 different measures of patient satisfaction. Nationwide, the number one complaint among patients is noise.
Noise disturbs the sleep of patients, and much of the noise is avoidable. Patients in a Washington State hospital – Washington State’s hospitals are ranked the noisiest for some reason – complaint that loud conversations between nurses and others taking in the hallway kept them up half the night.
Staff at Olympia's Providence St. Peter Hospital have been trying to pipe down for a few years now, and they’re not kidding. Annette Stier, director of the women’s and children’s clinic at Providence St. Peter Providence will clap to trigger one of the noise detectors installed in her section of the hospital when the clamour gets too loud.
"When the quiet light comes on, it tells me we need to slow our voices down, and we need to be quieter," she says.
Quiet is particularly important in this section of the hospital, in which some of the facility’s most vulnerable are struggling to get well. Premature babies, for instance, are highly sensitive to noise and will jerk violently when noise startles them. Sometimes loud noise will trigger a reflexive action that makes them hold their breath. These physical reactions to noise can cause them to use up their stores of glucose, which will need to be replaced via IV drip. In their case, noise is downright detrimental to their well-being.
Providence St. Pete’s has installed noise-absorbing materials in many of its wards, reduced the number of overhead pages, and instituted afternoon quiet hours. Other hospitals are beginning to report similar efforts, although it’s a rough road for many of them. Noise has been a part of the hospital backdrop for decades.
Paul M. Schyve, M.D., Senior Advisor, Healthcare Improvement at The Joint Commission – an organization based in Chicago that certifies quality and safety at hospitals nationwide – says that noise in hospitals isn’t just aggravating, it’s potentially dangerous to patients and staff.
"There's more machines with more alarms, and essentially they become confusing and overwhelming to the people that are working in that setting, so there may be, literally, in some settings, an alarm going off all the time, and frequently more than one alarm."
Each manufacturer puts a different set of bells and whistles on its medical devices, each one designed to be more alarming than the competitor's. Schyve says that essentially, the brain habituates to background noise that's always there. So if alarms are going off all the time, sooner or later that alarm actually registers less in your brain than it did originally.
It's a phenomenon known as "alarm fatigue."
Nationwide, the Food and Drug Administration reports about 140 deaths a year related to patient alarms. In many cases, medical staff ignored or failed to notice a key alarm.
The Joint Commission plans to make alarm fatigue a top priority for improving hospital care.
Schyve says alarms on medical devices are a vital part of health care, but he says it will take cooperation of hospitals and equipment manufacturers to find a way to make essential alarms rise above the noise.
For many hospitals across the U.S., problems in managing noise is inherent in the structure itself – narrow hallways with patient rooms crowded together, and nurses gathering at centralized work stations whose conversations ricochet off solid surface walls and into patients’ rooms.
When multiple conversations are going on, those doing the talking are apt to raise their voices to be heard over the others, adding to the hospital’s high decibel background noise. The result is a cacophony of sound from which patients cannot escape, and studies show it is lengthening recouperation time and in some cases, creating new health problems.
Although many hospitals are making an effort to instruct nurses and other staff to lower their voices when they talk, the acoustical problems inherent in these old buildings make quieting noise difficult. While sound abatement material is being introduced to some hospitals who have committed to addressing the noise problems, nurses are being assigned to work alone or in pairs at much smaller, less chatty and less centralized work stations.
Ironically, concerns over noise in hospital settings is nothing new. In 1859, Florence Nightingale was a fierce protector of peace and quiet among the ill, calling unnecessary noise “the most cruel absence of care which can be inflicted either on sick or well.”
Ms. Nightingale would be appalled to spend even a few minutes in a modern hospital, as machines and electronic gadgets have proliferated in the health care environment and hospitals have become noisier in modern times, rather than quieter.
Posted by Liz Ernst on Fri, May 04, 2012 @ 11:09 AM
New studies in hearing loss are increasing steadily, and the scientific world in scrambling to understand, and hopefully come up with some answers to the effects of man made noise on human hearing.
One researcher - Manfred Auer of Berkeley Lab’s Life Sciences Division - caught my eye with this succinct comment: "Finding a way to regenerate hair cells is the Holy Grail of research; We're born with just 16,000 hair cells in the cochlea, and every passing subway train kills a few of them."
Finding a way to regenerate the delicate inner ear hair cells is work Auer and other researchers are dedicating large chunks of time and resources to, as the industrialed world suffers greater degrees of hearing loss each year.
IIOne out of a thousand children in the United States is born IIdeaf; ten percent of all people living in industrialized nations IIsuffer from severe hearing loss — 30 million in the U.S. alone. IIThese are pressing clinical reasons to learn just how hearing IIworks and why it fails.
II"Hearing in humans is a remarkable faculty," says Auer "It works IIover six orders of magnitude, from a whisper to the roar of a IIjjet engine. If it were just a little more sensitive, we'd be able IIto hear the atoms colliding with our eardrums — in other IIwords, our hearing is about as sensitive as we can stand IIwithout going crazy."
IIHearing is also remarkable for its ability to adapt to constant IIloud noise yet still manage to pick out barely distinguishable sounds, "like being able to follow a single conversation across the room at a cocktail party, or hearing someone shout at you over the noise of a rock band," says Auer.
And humans can pinpoint the source of a sound to within less than a degree: one ear hears the sound slightly before the other, and the brain calculates the direction from the offset. But the difference in arrival times is less than a millionth of a second, a thousand times faster than most biochemical processes; thus hearing must depend on direct mechanical detection of sounds instantly translated into nerve signals.
The inner ear's hair cells are the key. They convert mechanical responses into electrical signals that trigger adjacent neurons in the brain — a prime example of a phenomenon, fundamental in tissue and cell biology, known as mechanosensation. Hair cells are embedded in the epithelial lining of the cochlea, where they respond mechanically to sound vibrations; others in the nearby vestibular labyrinth move in response to radial and linear acceleration and are the source of the sense of balance.
Thus beyond practical concerns lie basic scientific questions about the exact molecular composition and three-dimensional architecture of hair cells and related entities. A uniquely powerful tool for exploring biological structures at this subcellular but supramolecular level is electron microscope tomography — electron tomography for short.
A Hairdo for Hearing
The part of the hair cell that mechanically responds to vibration (or acceleration) is a bundle of fibers called stereocilia, sticking out of the top of the cell like a radical hairdo. In zebrafish the stereocilia are arranged in stair-step fashion. The tallest shaft, made of bundles of cylindrical microtubules, acts like a tent pole to support the development of all the others, which are made of bundles of the protein actin. Each actin-based fiber is shorter than the one next to it, and the tip of each lower fiber is attached diagonally to the side of the adjacent taller fiber by a fine filament called a tip link.
When vibration pushes against the bundle of stereocilia the fibers lean over, stretching the tip-link filaments. This pulls open nearby channels in the fibers (one or two per fiber), allowing potassium ions to flow into the fiber and down to the body of the cell. The electrical balance between calcium and potassium ions in the cell is instantly changed, triggering a signal to adjacent neurons.
If the hair bundle remains bent by persistent noise, a higher level of calcium in the cell signals the structural protein myosin, also present in the stereocilia, to slide down along the actin fibers. By resetting the tension on the tip-link springs in this way, hair cells can adapt to sustained noise levels.
"There are two ways hearing can be damaged by loud noises," Auer says. "Noise can stress the stereocilia bundle so much that the tip links break. However they usually grow back in 24 hours — this is the rock-concert effect, where hearing loss is temporary. But loud noises can also shear off whole bundles of stereocilia. In mammals these can't regenerate, and the loss is permanent."
Finding a way to regenerate hair cells, says Auer, "is the Holy Grail of research. We're born with just 16,000 hair cells in the cochlea, and every passing subway train kills a few of them."
Taken individually, the images of stereocilia from which Auer and his colleagues construct electron tomographs don't look much different from the many other microscopic studies of these structures — including blobs near the tips of the fibers that researchers customarily dismissed as "dirt." But, says Auer, "We think there is no such thing as dirt."
Because electron tomography allows "dissection in silico" Auer's group has been able to analyze these mysterious artifacts, giving rise to provocative hints of unsuspected tip-link structures — including whether there may be more than a single tip link between fibers, how tip links are structured, and what protein or proteins constitute the tip links.
"Until lately, the only protein firmly associated with stereocilia tip structures besides actin was myosin. Now we have 50 candidates — all because we could look at that 'dirt' in 3-D." Auer and his collaborators have developed good evidence for just which proteins are involved in tip-links and in other links among stereocilia. They plan to publish their findings soon.
And That's Just the Beginning
"For years, because they have understandably concentrated on disease organisms, microbiologists ignored the most basic condition of bacterial life, which is that bacteria live in communities," Auer says. Already electron tomography studies have revealed fascinating and unsuspected features of the bacterial communities known as biofilms. Contrary to what most biologists have thought, some biofilms — supposedly made up of independent bacterial cells — have many of the hallmarks of organized tissues.
Indeed, Auer says, "a biofilm is a prokaryotic version of a tissue," and he plans to publish research results soon, demonstrating these similarities in startling detail.
Because electron tomography can bridge the gap between ultrahigh-resolution protein structures and the large-scale organization of cells and tissues available to the light microscope, Auer says, "I would contend that electron tomography will play a major role in investigating all aspects of biology — in structural biology, cell biology, proteomics, biochemistry, physiology, pathology, evolution, everything. Once you have this new toy, you can apply it to all these questions."
Posted by Liz Ernst on Thu, May 03, 2012 @ 12:55 AM
With concerns raised and studies forged in recent years on health and learning problems experienced by children exposed to loud noise, it should come as no surprise that teachers are falling victim to noise induced hearing loss, caused by long hours spent in high decibel classrooms and gymnasiums.
However, it does come as a surprise, at least to school district administrators in Canada who have been testing teachers yearly for hearing impairment. This year, officials say, is the first time they have noted a marked rise in hearing loss among teachers.
Winnipeg houses Canada’s largest school district (they call them divisions), and this is where the teachers with noted hearing loss first surfaced.
“It’s a warning sign to us that we need to do something,” Division Director Eugene Gerbasi recently told CBS News. “If we don’t do something, individuals could potentially lose their hearing,” Gerbasi said.
So why no uproar about the children exposed to the same conditions as the teachers? They’re not at risk because they do not log the long hours, year after year, in gyms, band classes, shop classes and other high decibel classrooms. In some schools where teachers were tested, the loudest classes include choir, music, band, and industrial arts. However, the gym appears to be the worst culprit across the board, with noise levels routinely measured above 90 decibels.
Under Manitoba's workplace legislation, noise levels cannot exceed 85 decibels.
The same problem affects teacher worldwide, and American teacher are expected to be exposed to similar noise overages as their Canadian peers, although many U.S. public schools no longer have the funds to support band, choir, and industrial art classes, and no evidence of routine hearing tests being performed on U.S. teachers could be found, American teachers who teach gym and band classes are reporting moderate to profound hearing loss over time, and many are candidates for cochlear implants.
However, prevention is the name of the game when it comes to noise pollution and protecting our hearing,
A study by researchers at the University of Toronto suggests that music teachers are routinely exposed to noise levels that could result in hearing loss. Gerbasi told CBS News that teachers and staff at the Winnipeg School Division will soon have to start wearing protective hearing devices.
Nick Dyck, a gym teacher for more than 20 years in the Winnipeg Division, says he has lost the ability to hear certain noise levels and participate readily in conversations because he has to strain to hear people. Dyck, now a physical education and health consultant for another Winnipeg school division, says he believes his hearing loss is related to the noise levels he experienced as a gym teacher for two decades.
Another study led by research associate Alberto Behar, and electrical and computer engineering professors Hans Kunov and Willy Wong, generate findings that exposure to general noise over the course of an eight hour day is marginally acceptable, elevated noise levels during teaching periods can cause damage to the inner ear.
"The hair cells of the inner ear simply crumble under the load, and they don't grow back again," Kunov explained.
The Ontario Occupational Health and Safety Act caps acceptable noise levels at 90 decibels – the equivalent of a power lawn mower – for more than eight hours in any 24 hour period. Noise levels on the job should not exceed 90 decibels -the equivalent of a power lawn mower-over eight hours of a 24-hour period.
In their study, Wong and his colleagues used noise dosimeters to measure noise exposure to 18 teachers from 15 Toronto high schools, and found that peak noise levels exceeded 85 dB for 78 per cent of the teachers. In an average eight-hour day exposed to these decibel levels, their findings stated that 39 per cent of the teachers in the study faced potentially harmful noise levels, and acoustics are as much to blame as the noise itself.
“The world is louder than we think,” Wong exclaimed while reviewing their findings.
Most classrooms are constructed of concrete blocks and linoleum flooring, which produces a highly reflective sound surface. Wong said that schools should consider protective measures such as sound absorbing materials and carpet, and teachers might also want to wear protective earplugs and consider periodic hearing checks.
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Posted by Liz Ernst on Tue, May 01, 2012 @ 03:37 AM
Sound, or more specifically, noise, is an invisible pollutant that can harm our ears, our hearing, and our health.
Think back to the last time you went to a rock concert or a particularly high volume club; when you left, did you pay much attention to the peculiar ringing in your ears as you headed back to your car, maybe even after you returned home? The sound around you were muffled for a short while, replaced with a buzzing inside your head, almost as if your ears were screaming.
In a way, they were.
IISo, what do we need to know about protecting out ears from IIloud noise, and what do we do when the ringing never stops?
IINoise pollution is encroaching on the everyday lives of all of IIus, and the more we understand about how noise effects our ears, our hearing, and our health and well being, the more IIlikely we are to take action to make changes.
II
Hair cells within the inner ear.
Noise levels louder than a shouting match can damage the hair cells of the inner ear. These delicate hair cells Hair cells within the inner ear contain act as the "gatekeepers of our hearing. When sound waves hit them, they convert those vibrations into electrical currents that the auditory nerves carry to the brain. Without hair cells, there is nothing for the sound to bounce off - compare it to trying to make your voice echo in the desert.
Hair cells reside in the inner ear inside the shell-shaped cochlea. Bundles of hair-like extensions, called stereocilia, rest on top of them. When sound waves travel through the ears and reach the hair cells, the vibrations deflect off the stereocilia, causing them to move according to the force and pitch of the vibration. For instance a soft piano sonata would produce gentle movement in the stereocilia, while heavy metal would generate faster, sharper motion. This motion triggers an electrochemical current that sends the information from the sound waves through the auditory nerves to the brain.
When you hear exceptionally loud noises, your stereocilia actually become damaged and mistakenly keep sending sound information to the auditory nerve cells. After spending time at a rock concert, a loud club, an active race track, an air show, an industrial plant with unmitigated chillers or machinery, or even in heavy traffic, the ringing happens because the tips of some of your stereocilia actually have broken off. You hear the false currents in the ringing in your head, called tinnitus. However, since you can grow these small tips back in about 24 hours, the ringing improves and goes away over time.
There are two ways hearing can be damaged by loud noises, according to Manfred Auer of Berkeley Lab's Life Sciences Division. Noise can stress the stereocilia bundle so much that the tip links break, which Auer refers to as the rock-concert effect, where hearing loss is temporary and the stereocilia tips grow back.
However, loud noises can also shear off whole bundles of stereocilia. In mammals these can't regenerate - the loss is permanent.
Repeated exposure to loud noises can kill the hair cells entirely. So what? We have 16,000 of them in each cochlea, but that number pales in comparison to the eye's 100 million photoreceptors, which do to light what hair cells do to sound. In addition, once those hair cells die, we cannot growth them back. This is why protecting your ears is essential.
How loud is too loud? Sound is measured in units called decibels. Decibels measure the power of sound, rather than the amount. Safe sound levels are considered below 85 decibels. Here's another rule of thumb: If you have to shout to hear someone an arm's length away, the sound is probably above that safety threshold.
Repeatedly crossing that 85-decibel threshold can have unpleasant consequences. While the ringing in your ears from a loud noise is usually brief, for more than 12 million Americans, it never stops, according to the American Tinnitus Association. Chronic tinnitus can be a symptom of infections, high blood pressure, even compacted earwax, but it is commonly associated with noise-related hearing loss.
There are a few simple ways to safeguard your hearing. First, be aware of the noise levels around you. If you know you're going to be in a loud environment, wear earplugs to protect your ears. Also, notice how close you are to the source of loud noises and how long you're exposed to them. And pay attention to the ringing in your ears. Our bodies are sometimes more fragile than we think.