Tinnitus (Ringing in the Ear)

One well-known effect of overexposure to noise is hearing loss, or the inability to hear certain sounds. But another risk is a phenomenon that is just the opposite: perceiving sounds when there are none. This perception of sound when no external sound is present is called tinnitus, or "ringing in the ear." 

What Does Tinnitus Sound Like? 

People with tinnitus hear noises in their ears. Each person with tinnitus experiences it differently. "Tinnitus" is from the Latin word for "ringing," and to some people the noise does indeed sound like ringing. Others describe their ear noise as roaring, rushing, hissing, chirping, beeping, buzzing, whistling, or clicking. The sound might be high-pitched, low-pitched, or multi-toned, or it might sound like static. It might seem to be in one ear, both ears, or inside the head. The sound might be constant, or it might come and go. It might be just barely noticeable, or it might seem screamingly loud. 

Nearly everyone experiences ear noise; in total silence, most people will report hearing faint buzzing, pulsing, or whirring sounds, the normal compensatory activity of the nerves in the hearing pathway. It's when these sounds are intrusive that it becomes tinnitus. 

What Causes Tinnitus? 

Tinnitus may be caused by various drugs, ear disorders, infections, injuries, or psychiatric disorders, but the most common cause by far is loud noise, such as from explosions, gunfire, amplified music, farm machinery, or emergency sirens. Many rock musicians develop tinnitus, and it is common among combat veterans. Ninety percent of people with tinnitus also have some degree of hearing loss. 

Like hearing loss, tinnitus can occur temporarily, brought on by an episode of too much noise, or it may happen after years of overexposure to noise. It can appear suddenly or gradually. 

What Is It Like to Have Tinnitus? 

Tinnitus is a subjective experience. Similar to the experience of pain, the annoyance of tinnitus cannot be measured objectively. Some people hardly notice the noise unless they consciously turn their attention to it. For others it may disrupt sleep and concentration, and can cause depression and emotional shifts. According to the American Tinnitus Association, about 25% of those with tinnitus find it disturbing enough that they seek medical attention for it, and for about 4% of sufferers, it is so debilitating that it seriously interferes with normal daily functioning. For a few people the experience is so agonizing that they are driven to consider suicide. 

How Is Tinnitus Treated? 

Tinnitus is a symptom, not a disease, and there is no cure. Even in some cases where the auditory nerves have been severed (during the removal of a tumor from the inner ear, for example), so that the patient loses all physical hearing, tinnitus can persist. 

There are a range of treatment options for chronic tinnitus; no one treatment works for everyone. Many treatments focus on helping the person learn to coexist with it, using a variety of stress management and relaxation techniques, counseling, and sometimes antidepressants or other drugs. Some people find it helpful to mask the ringing in the ear by using white noise, and there are in-ear white noise devices made for this purpose. 

Two treatments, tinnitus retraining therapy and Neuromonics, combine directive counseling with white noise or music that is individually engineered for the patient's audiological profile, to teach the brain circuitry to filter out the tinnitus signals. These treatments take six months to two years and cost several thousand dollars. 

Temporary Ringing in the Ear? 

If you experience temporary ringing of the ears from an exposure to loud noise, consider it a warning sign. First, immediately leave the loud environment, or put in ear plugs if that is not possible. Next, rest your ears for 24 hours, meaning no loud sounds at all, to give your ears a chance to recover. And lastly, next time you are in a similar environment in the future, be sure to wear hearing protection. There are plenty of tinnitus sufferers who will tell you that you don't want their nightmare. 

From NoiseHelp

Noisy environments make young songbirds shuffle their tunes

A baby songbird prefers to learn the clearest versions of songs he hears and uses them to build his personal playlist for life. As a result, noise, from nature and humans, influences which songs a bird learns to sing and can create lasting changes to his species' top tunes, the study's results suggest. 

"There's been an enormous amount of interest in how anthropogenic factors affect the channels animals use for communication and in particular how human noise affects birdsong," said Duke University biologist and study co-author Steve Nowicki. "As far as we know, this is the first study that can link noise to cultural evolution of bird song." 

The team designed the study to test a 30-year-old hypothesis suggesting that young birds memorize and later sing the clearest songs they hear during their critical learning period. In the experiment, Nowicki and his collaborators collected nine male, swamp-sparrow nestlings and hand-raised them in a soundproof room. Twice a day for 12 weeks, the birds heard recordings of 16 song types sung by adult males of their species. Eight song types were degraded, or noisy, by being broadcast across a typical sparrow territory of 25 meters and then re-recorded. The other eight were clean copies of similar-sounding, but different songs. When the birds later matured and began to sing, they only repeated the clear songs. 

"It wasn't too surprising that the sparrows preferred them," said Duke behavioral ecologist Susan Peters, lead author of the study. "What is exciting is how clear-cut the results are. All of the birds learned clear songs and none learned any of the degraded songs," she said. The results appeared online June 20 in the journal Biology Letters. This "simple" but "elegant" experiment "says a great deal about how birds put to use their extraordinary ability to hear small-time differences," said Eugene Morton, a biologist at York University in Canada who was not involved in the study. The birds use this ability to learn songs that transmit through their habitat with the least amount of degradation. "In this way, the birds themselves reject songs less well suited to their environment," an example of cultural selection, Morton said. 

Scientists consider the song shifts to be selected culturally, rather than naturally, because the songs are learned, not innate. "This is important because cultural selection can happen more rapidly than natural selection," Peters said. "It helps to explain why birdsong is so diverse," and shows evidence that song variation depends on the bird's habitat. She added that noise from cities and humans would have the same effect on song selection. "We already knew that some birds can adjust some features of their song when confronted with anthropogenic noise, and now we know that this may have an impact on cultural transmission of their song," she said. If naturally noisy songs are less desirable to learn, then songs shaped by human noise are probably less likely to be passed down and learned generation after generation. "Who would have thought that a swamp sparrow song might be affected by human activity?" Peters said. 

Source: Phys.Org

Noise-absorbing windows

The noise of aircraft taking off, road traffic or a booming discotheque often drive inhabitants of the neighborhood to a nervous frenzy. The first-ever windows with active sound insulation offer much-needed relief to local residents in their homes and offices.

When an aircraft takes off over your roof every five minutes, the noise makes it impossible to hold a conversation. Windows can’t provide adequate protection against this type of noise pollution.

A double or triple layer of glass will absorb the high frequencies, but can do nothing against low-frequency noise such as that produced by aircrafts or thrumming bass tones of disco music. This would normally call for panes of glass so thick and heavy that their use would be almost prohibitive in lightweight constructions or extensive curtain-wall facades.

Researchers at the Fraunhofer Institute for Structural Durability and System Reliability LBF and Darmstadt University of Technology have found a solution, namely a new type of soundproof window. “Tests have shown that our windows are capable of lowering noise levels by an average of six decibels at frequencies between 50 and 1000 hertz. The perceived noise indoors is only half as loud,” says Dr. Thilo Bein, who manages the institute’s department of energy, environment and health. “We have even been able to reduce the volume of certain test signals by up to 15 decibels.” The experts have predicted a reduction of up to 10 dB for the engine noise of passenger aircraft in the frequency range below 1000 Hz.

When noise waves meet the walls of a building, they can be propagated to the interior by various routes. One is by causing the windows to vibrate, thus carrying the noise into the building. The other is by transmitting sound waves to the interior via the bridges in the structure where the curtain-wall elements are attached to the frame of the building. In both cases, the researchers have found a way to prevent the propagation of sound energy. Acceleration sensors attached to the window panes measure the vibrations generated by the noise.

A thin chip of piezoelectric material also attached to the window counteracts the vibration by generating an oscillation at the same pitch but in the opposite sense to that measured by the sensor – causing the pane to move in the opposing direction. “We have devised a similar solution for the points where the outer cladding is attached to the frame of the building. In this case, a stack of piezoelectric chips, rather than a single piezoelectric strip, counteracts the impinging force,” says Bein.

Source: Phys.Org