Cruising with the top down? Cover your ears

Riding in a convertible with the windows down appears to expose people to noise levels that, over time, can damage hearing, according to a study presented today at the annual meeting of the American Academy of Otolaryngology-Head and Neck Surgery Foundation in San Diego.

Dr. Philip Michael, a British ear, nose and throat surgeon who loves his own convertible, assessed noise levels in seven different cars traveling at speeds of 50, 60 and 70 miles per hour. He found drivers were consistently exposed to noise levels between 88 and 90 decibels. Previous research suggests that repeated exposure to noise over 85 decibels can result in hearing loss.

However, keeping the car windows up, even with the top down, reduced noise levels to 82 decibels. "A large component of the noise you are exposed to is wind noise," he said.

But the noise is generated from a variety of sources, Michael said, including from the engine, exhaust and tires and from other cars and trucks on the road. While Michael did not study noise from surrounding traffic, he suggests that driving slower may actually increase noise exposure.

"If there is a lot more traffic you can get exposed to more noise," he said. "If you're driving slower, you may be overtaken by trucks, which cause more noise and take longer to go around you."

More research should be done to test hearing before and after a drive, he said. Studies should also be conducted on noise exposure to people who drive enclosed cars with the windows down.

-- Shari Roan

Photo credit: BMW Group / Associated Press 

What will become of American Sign Language?

Today's story in the Los Angeles Times describes the popularity of cochlear implant surgery for babies and toddlers as soon as they are identified as deaf. Due to advances in newborn screening of hearing disorders and the safety of the surgery, more parents of deaf children are opting to have their children implanted as early as age 1. The swift decision means fewer families and their deaf children are bothering to learn American Sign Language.

That raises a concern over what will happen to sign language in the years ahead. About 400,000 Americans are fluent users of American Sign Language.

Until the past five years or so, cochlear implants were considered risky for young children. Some teachers of the deaf recommended that parents wait and let the child decide whether to get implants or use sign language. But such advice comes with a cost: A child who waits too long to hear might never become proficient in oral language. As scientific evidence accrues that children learn spoken language better if implanted before age 3, the recommendation to wait has faded.

Still, some experts advocate learning sign language even if children receive implants. Learning sign language is a safeguard that allows a young child to develop communication skills prior to receiving the implant. And sign language is there if, for any reason, the implants do not help a child sufficiently.

“We’re trying to impress upon the medical community and on those who are naysayers that you can develop American Sign Language and you can develop spoken language at the same time. The brain has the capacity to do that,” says Debra Nussbaum, coordinator of the cochlear implant education center at Gallaudet University in Washington, D.C., a famous college for deaf people.

“It’s remarkable technology but I do think it’s been overplayed and hyped a little more than it should be for all children,” Nussbaum says of cochlear implants. “The outcomes vary among children. I have seen kids who do great and others who still can’t speak well.”

Audiologists, doctors and teachers agree that the foremost predictor of success is how hard parents, audiologists and educators work with the child to make use of the implants.

“We don’t want to present to parents that [cochlear implants] is a cure,” says Margaret Winter, coordinator of the Children’s Auditory Research and Evaluation Center at the House Ear Institute in Los Angeles, which performed the first pediatric cochlear implant. “We are giving them another avenue to access sound, and what they do with that information depends on many things we don’t understand. We know there is more to it than just putting a cochlear implant in a child.”

-- Shari Roan

Photo: Marieta de Lara adjusts the cochlear implant on her son, Tyler, 3. Credit: Anne Cusack  /  Los Angeles Times

Friends, Romans, countrymen, lend me your (right) ear

The answer to your question may depend on which ear you ask. We tend to offer our right ear to speakers and are more likely to say yes to a request addressed into it, reported Italian researchers in a study published in the journal Naturwissenschaften.

Although knowledge of right-ear dominance is nothing new, how the results were generated in this study was: The scientists talked to strangers in nightclubs.

Right-ear preference is one of the best-known asymmetries in humans, transcending gender, ethnicity, age and right- or left-handedness. It is thought to be due to the right ear’s speediness in transmitting information to our brain’s left hemisphere, which dominates in processing language.

Until now, however, most studies on the phenomenon were performed in laboratory-controlled settings, not more “natural” environments.  

To change this, researchers Daniele Marzoli and Luca Tommasi of the Gabriele d'Annunzio University in Italy gathered observational evidence from what they called an “ecological situation”: noisy Italian discotheques.

First, the researchers watched 286 clubbers while they were talking, and observed that 72% of all interactions happened on the listener’s right side.

Next, the researchers had a woman approach 80 men and 80 women, mumble a meaningless request and observe which ear the listener offered. (She then asked for a cigarette.) 

Overall, 58% of the subjects lent their right ear, with females showing a significant preference for doing so. In this situation, when the people who were approached chose the ear they offered, the woman was just about as likely to get a cigarette regardless of which ear she spoke into.

In the final leg of the experiment, the woman went up to a person and chose which ear she spoke into. When this was done, the likelihood of the woman being given the cigarette doubled with requests that were spoken into the right ear: 34 of 88 clubbers offered a cigarette to an asker addressing the right ear, and only 17 of 88 clubbers did the same when addressed on the left.

Why should this be? It is thought that activation of the left and right brain hemispheres correspond with positive and negative judgments, respectively. This asymmetry is linked to two motivational systems: “approach” in the left and “avoidance” in the right. 

The data, which suggest specialization of different sides of the brain for different emotions, are consistent with previous findings. For example, one study from 1991 found that subjects showed a better memory of arguments with which they agreed when the sentences were heard through the right ear, and better remembering of disagreements heard through their left ear.

However, the scientists caution, “Unequal distribution of sound sources in space, type of music played, [or] effect of alcohol intake” all may have had an effect on results.

-- Shara Yurkiewicz

Gene influencing age-related hearing loss

If you wonder why Gramps' hearing has gone to the dogs and Grandma's hearing has not -- well, there could be a plethora of reasons. Such as lifetime exposure to loud noises, certain meds, certain medical conditions and more. Add genes to the mix. In a study reported in the journal Human Molecular Genetics, researchers at the local House Ear Institute, in collaboration with scientists at several other institutions (see list below), found several genes involved in hearing loss risk, most notably one called GRM7.

GRM7 carries instructions for a protein that is made in cells of the inner ear and is involved in receiving signals from nerves. A nerve-signaling chemical called glutamate attaches to this protein receptor -- and too much glutamate stimulation can damage the fragile hair cells key to hearing. Certain people, it appears, have a gene that directs formation of a receptor that's more sensitive to such damage.

Scientists have actually known for some time that there's a significant genetic contribution to the decay of hearing loss that comes with age -- but it's one thing to know that genes exist, quite another to have tracked any of them down. These days, what with the whole human genome sequenced and high-tech "chips" available for the scanning of tiny variations that exist between one individual and the next, such genes are easier than ever to find.

The study was conducted by Rick Friedman of the House Ear Institute as well as others from House, the Translation Genomics Research Institute in Phoenix, Affymetrix in Santa Clara and the University of Antwerp, Belgium. It involved genetic scans of more than 800 Europeans with age-related hearing loss and a similar number of people without it, for comparison.

By the way, hair cells are very pretty. You can learn more, and see a cool image, here (and also learn about the hope that one day hair cells could be regenerated).

Hair cells do their sound-transmitting job by moving in response to sound. Here's a bizarre movie one Brit scientist made of a hair cell dancing to "Rock Around the Clock."  (Make sure you listen to the soundtrack.)

-- Rosie Mestel   

Is there a tinnitus personality?

Tinnitus is a bedeviling condition that affects 50 million Americans to some degree, and 12 million of them severely. The causes and treatment of the condition have been the subject of much research, and some controversial studies have suggested that a person's state of mind has something to do how tinnitus is experienced. Now a new study also concludes that personality plays a role in how the condition affects people.

Tinnitus is often called "ringing in the ears." It's a subjective noise that is described by sufferers as the sound of ringing, crickets, whooshing, pulsing, buzzing or even music. If severe, it can greatly affect a person's quality of life and functioning. There has long been a perception that people just need to get used to tinnitus and those who accept the condition do better. Though it's not true that one simply has to get used to it --there are effective treatments -- the new study in the October issue of Ear and Hearing, the Official Journal of the American Auditory Society, found that people with tinnitus were found to be more socially withdrawn, reactive to stress, alienated and less self-controlled. People who reported being more annoyed by tinnitus were also more socially withdrawn. The researchers, from New Zealand, conclude that successful treatment of the condition may start with evaluating how much a person is aware of the noise (which may be influenced by personality) and then working on strategies to decrease awareness.

For more information on the condition, go to the web page of the American Tinnitus Assn.

-- Shari Roan

Photo credit: Christine Cotter / Los Angeles Times

Hearing loss: Listen up ...

... and turn it down. Some 32.5 million people have a hearing loss, and for 30% of them, the loss could have been prevented. “Exposure to noise damages the microscopic hair cells found in the inner ear, which play a critical role in our ability to hear,” says Dr. Jose Fayad of the House Ear Institute in Los Angeles, which investigates hearing loss at the cellular and molecular level. “The damage can be from a brief but intense noise, but is most often caused by regular exposure to excessive sound over the course of several years.”

Normal conversation comes in at a noise level of about 50 to 70 decibels, and no matter how boring or inane, it won’t hurt your ears. A motorcycle or lawn mower is 85 to 90 decibels, and eight hours of exposure to that level of sound can begin to damage hearing. But get the noise level up to 100 decibels, and it only takes 15 minutes for damage to begin. A rock concert, typically 110 to 120 decibels, or a jet takeoff at 119 to 140 decibels, starts doing damage in minutes.

The Institute has some tips. If you’re exposed to loud noise, over 85 decibels, take periodic 15-minute quiet breaks. If you have to raise your voice to be heard, you’re in a potentially dangerous sound environment.

If you can’t get away from the noise, wear hearing protection, such as earplugs. And if you’re at a rock concert, move away from the amplifiers or speakers.

--Susan Brink

Images: Courtesy of House Ear Institute (pie chart created following guidelines from the National Institute for Occupational Safety and Health)