Hidden Hearing Loss

Loud sound may pose more harm than previously thought

The Associated Press (AP) reports that “[s]cientists have been finding evidence that loud noise — from rock concerts, leaf blowers, power tools, and the like — damages our hearing in a previously unsuspected way.”  The damage “may not be immediately noticeable, and it does not show up in standard hearing tests,” the AP adds, but according to Harvard researcher M. Charles Liberman,” it can rob our ability to understand conversation in a noisy setting [and] may also help explain why people have more trouble doing that as they age.”  The condition is called “hidden hearing loss,” and Liberman adds that “[n]oise is more dangerous than we thought.”

The AP interviews Matt Garlock, a 29-year old systems engineer who is “a veteran of rock concerts.”  Garlock complained of not being able to hear friends in a crowded bar, but when he got his hearing checked his test results were normal. The AP writes that Liberman’s work “suggests that there’s another kind of damage that doesn’t kill off hair cells, but which leads to experiences like Garlock’s.”  Specifically, Liberman believes that loud noise damages the delicate connections between hair cells, called synapses.  He adds that animal studies show that “you could lose more than half of your synapses without any effect on how you score on an audiogram,” but if you lose enough synapses, it “erodes the message the nerves deliver to the brain, wiping out details that are crucial for sifting conversation out from background noise.”

The end result is that people like Garlock recognize that they have a problem but their hearing appears to be fine when they take conventional hearing tests. Fortunately, Liberman says that “[o]ne encouraging indication from the animal studies is that a drug might be able to spur nerves to regrow the lost synapses.”  [Note: This article notes that Liberman has a financial stake in a company that is trying to develop such treatments.]  But while treatment for hidden hearing loss may be available in the future, what can be done now?  Liberman states that his work “lends a new urgency to the standard advice about protecting the ears in loud places.”  As always, prevention is better than treatment.

 

Another Silent Spring

By Daniel Fink, MD, Chair, The Quiet Coalition

In 1962, Rachel Carson’s “Silent Spring” described the harmful effects of insecticides and herbicides on birds, beneficial insects, animals, and humans.  Her book helped start the environmental movement. For too many people, this will be another silent spring, caused not by a dearth of birds but because people can’t hear birds sing. They have hearing loss from another environmental pollutant, noise.

Carson described how nature’s balance controlled pest species naturally, and how these species became problems only when humans changed the environment. She noted the difference between apparent short-term safety of agrichemicals and longer-term danger. People could get sprayed with pesticides or even ingest them without apparent immediate harm, with cancer and birth defects coming later.

If Carson were alive today, she might write about noise pollution, which interferes with animal feeding, communication, mating behaviors, and navigation in forests, fields, and oceans, and causes hearing loss and other medical problems in humans.  In nature’s quiet, animals developed exquisite hearing to find food or avoid being eaten. An owl can find a mouse under a foot of snow, and zebras can hear lions approaching in the veldt.

Humans are also born with excellent hearing.  Brief exposure to loud noise usually doesn’t cause obvious auditory damage in humans, but longer or repeated exposure does. The relationship between noise and hearing loss was first noted in medieval times in bell ringers and miners, then in boilermakers during the industrial revolution.  Noise wasn’t a widespread problem, and except in large cities life was usually quiet.

Industrialization, mechanization, and urbanization made life noisier.  Noise was recognized as a public health hazard in the early days of interstate highways and jet travel, but was also considered an environmental pollutant. In 1972 Congress passed the Noise Pollution and Abatement Act, empowering the Environmental Protection Agency (EPA) to establish noise standards and require noise labeling for consumer and industrial products.

During the Reagan administration, however, Congress defunded EPA noise control activities. Little has been done since to control noise, and our country has gotten noticeably louder. Sound levels of 90-100 decibels or louder are reported in restaurants, clubs, retail stores, movie theaters, gyms, sports events, concerts, and parties, from sirens, vehicles, landscape maintenance equipment, and construction, and for those using personal music players.

The National Institutes of Health states that prolonged exposure to noise at or above 85 decibels can cause hearing loss. This is misleading, because no exposure time is given and hearing damage occurs at much lower levels. The 85-decibel standard is an occupational noise exposure standard, not a safe noise level for the public.. The EPA adjusted the occupational standard for additional noise exposure outside the workplace to calculate the noise level for preventing hearing loss to be a daily time-weighted average of only 70 decibels.

Hearing is the social sense, required for spoken communication. About 40 million American adults age 20-69 have noise induced hearing loss, half of them without noisy jobs. Why is this happening? They are exposed to loud everyday noise.  Cumulative noise exposure eventually causes hearing loss, affecting 25% of those in their 60s, half in their 70s, and 80% in their 80s, and is correlated with social isolation, depression, dementia, falls, and mortality. Due to denial, stigma, and cost only 20% of older Americans with hearing loss acquire hearing aids, after an average seven-year delay, and 40% of people with hearing aids don’t use them much, largely because hearing aids don’t help users understand speech well in noisy environments.

Preventing noise-induced hearing loss is simple: avoid loud noise. If it sounds too loud, it is too loud. Free or inexpensive smart phone sound meter apps make it easy to measure sound levels, but if one can’t converse without straining to speak or to be heard, ambient noise is above the auditory injury threshold of 75-78 decibels and auditory damage is occurring.

A quieter world is easily attainable. Whisper-quiet dishwashers, cars with quiet interiors and exhausts, the Airbus A380, and a few quiet restaurants and stores prove this.   Effective noise control technologies have long existed, including noise reduction via design and material specifications and sound insulating, isolating, reflecting, diffusing, or absorbing techniques.  Indoors, all that may be necessary is turning down the background music volume, which costs nothing.

In the 1950s and 1960s, half of all American men smoked and public spaces and workplaces were filled with tobacco smoke. When research showed that tobacco smoke caused cancer and heart disease, governments restricted smoking, leading eventually to today’s largely smoke-free society. Smokers can still smoke, but can’t expose others involuntarily to their smoke.

Noise causes hearing loss. Governments should set and enforce indoor and outdoor noise standards, to reduce each person’s daily noise dose. Adults have the right to make and listen to all the noise they want, but not where others can hear them. If we can breathe smoke-free air, we can make a quieter world, so future generations won’t have to endure another silent spring.

Dr. Fink is a leading noise activist based in the Los Angeles area.  He serves on the board of the American Tinnitus Association and is the interim chair of Quiet Communities’s Health Advisory Council and the founding chair of The Quiet Coalition, an organization of science, health, and legal professionals concerned about the impacts of noise on health, environment, learning, productivity, and quality of life in America.

Originally posted at The Quiet Coalition.

Do you have hidden hearing loss?

Dstanczyk87

Photo credit: Dstanczyk87

Not sure?  One halllmark of hidden hearing loss is having difficulty hearing when you are in a noisy setting.  Recently, the Associated Press asked the Mailman Center for Child Development at the University of Miami to prepare an exercise to help readers determine how well they can hear in a noisy background. Click the link to try the exercise and see if are showing signs of hidden hearing loss.

The CDC issues report on noise-induced hearing loss

and the facts are frightening. The Centers for Disease Prevention and Control’s (CDC) current issue of Vital Signs focuses on the dangers of noise on hearing health.  Among other things, the report states that:

  • 40 million Americans aged 20-69 years old have noise-induced hearing loss (NIHL). Hearing loss is the third most common chronic health condition in the US, and almost twice as many people report hearing loss as report diabetes or cancer.
  • 1 in 2 American adults with hearing damage from noise did not get it exposure to noise at work. Noise outside of work can be as damaging as workplace noise.
  • Too much loud noise, whatever the source, causes permanent hearing loss.
  • 1 in 4 Americans who report excellent hearing have hearing damage.  You can have hearing loss without knowing it.
  • The louder the sound, and the longer you are exposed to it, the more likely it will damage your hearing permanently.
  • Continual exposure to noise can cause stress, anxiety, depression, high blood pressure, heart disease, and many other health problems.

This fascinating if distressing report comes with easy to understand graphs and charts that clearly explain the dangers of noise exposure, who is most at risk, the high cost of hearing loss, how hearing loss occurs, and, most importantly, what can be done to prevent NIHL.  Because, in the end, one point is crystal clear: noise-induced hearing loss is 100% preventable.

Age doesn’t matter,

you could have hidden hearing loss (and not know it). WMAR Baltimore reports on hidden hearing loss, a relatively recently discovered hearing breakthrough that explains how people who pass hearing tests have problems hearing in noisy environments.  WMAR interviewed audiologists about this breakthrough, who said that “why patients can’t decipher speech in noisy situations has been unexplained, but a new breakthrough is changing that.”  The researchers who made the hidden hearing loss breakthrough studied young adults who were regularly overexposed to loud sounds, and found that “hidden hearing loss is associated with a deep disorder in the auditory system.”

It’s never too late to protect the hearing you have.  Exposure to loud sounds damages hearing.  Period.

 

Declining prevalence of hearing loss in U.S.? What do the data really show?

by Daniel Fink, MD

On December 16, 2016, an article appeared in the New York Times, Americans’ Hearing Loss Decreases Even With Ubiquitous Headphones, which focused on a study by Howard J. Hoffman, MA, et al. (Hoffman) that appeared in the respected medical journal JAMA Otolaryngology–Head & Neck Surgery. The study found that there was a declining prevalence of hearing loss in U.S. adults. The results were considered surprising, as the study showed that the rate of hearing loss in adults age 20-69 had decreased from 15.9% to 14.1%. The researchers, epidemiologists, and statisticians at the National Institute for Deafness and Other Communication Disorders, who conducted the study, are among the best in the world, and the data came from the Centers for Disease Control and Prevention’s well-respected National Health and Nutrition Surgery.

The results were considered surprising because two other recent federal reports, one in October 2015 from the President’s Council of Advisors on Science and Technology (PCAST) and the other in June 2016 from the National Academy of Science’s Institute of Medicine (IOM) (since renamed the Health and Medicine Division), emphasized that hearing loss, especially in older Americans, was a major national problem. Both of these reports cited an analysis by Frank Lin, MD PhD, Johns Hopkins University, that showed that 48 million Americans suffered significant hearing loss, with the prevalence increasing sharply with age.

I am personally involved in the question of what the facts are, since in an editorial in the January 2017 issue of the American Journal of Public Health I write about the inappropriate use of the 85 decibel occupational noise exposure standard, which should not be applied to the general public, citing Lin’s research and other studies that show increased hearing loss in young people age 12-19.

So, what do the data really show?

I am not an epidemiology expert like Mr. Hoffman and his distinguished co-authors. Their methods appear sound, their data sources as good as one can find in the epidemiology of hearing loss. The first caveat is that this study, as with all studies of the epidemiology of hearing loss in the pubic, is based on survey methodology. A group of 3831 participants are the study population, from which conclusions about the entire U.S. population were drawn. It would be too costly to test hearing in millions of people.

The second caveat is that there are newer techniques, currently only used in research and not yet in clinical use, demonstrating that before hearing loss can be detected by standard hearing tests (called pure tone audiometry), a phenomenon dubbed “hidden hearing loss” may have taken place. Hidden hearing loss has been found in young people and older adults. So while Hoffman’s study is encouraging, it may not be able to completely report what is really happening with Americans’ hearing.

The third point–not a caveat–is that Hoffman et al. studied adults age 20-69 and did not include young people under age 20. Those under age 20 may be the group most at risk of hearing loss due to ubiquitous use of personal music players at loud volumes. Two studies, using lower thresholds for measuring hearing loss than Hoffman et al. or Lin et al. used, found high levels of subclinical hearing loss (hearing loss greater than 15 decibels but less than 25 decibels) in young Americans. One from 1998 found that 15% of young people had measurable hearing loss, and the other from 2010 showed an increase in the prevalence of hearing loss to almost 20%. This is worrisome because studies of auditory acuity in young people traditionally found excellent hearing.

The fourth point also isn’t a caveat, but a quote from the last line of Hoffman’s abstract: “Despite the benefit of delayed onset of HI (hearing impairment), hearing health care needs will increase as the US population grows and ages.”

It’s great news that the percentage of Americans age 20-69 with hearing loss (the epidemiology term for this is “prevalence”) has decreased from 15.9% to 14.1%. But that still means that there are millions of Americans with hearing loss–and that’s too many! Further, subclinical hearing loss appears to be increasing in young Americans, and, as the Hoffman study notes, hearing loss in older Americans is a significant health problem.

Finally, a point of contention: noise exposure is a major cause of hearing loss, and not aging as is implied in the study. Why would men have nearly twice as much hearing impairment (18.6%) as women (9.6%)? Is it an effect of testosterone levels on the auditory system, in which case one might actually expect hearing to improve as men get older, or is it the result of more noise exposure from work and recreational activities in men than women? Noise and hearing loss are still major problems in the U.S. and in the world, and the non-auditory effects of noise on health, which are coming into greater focus, continue unabated. 

So yes, the prevalence of hearing loss in American adults may be declining, but when Lin’s analysis showed that approximately 25% of adults in their 60s, 33% of adults in their 70s, and half of those over age 80 have significant hearing loss–data cited in the PCAST and IOM Committee reports–it is obvious that there is still a major problem and still much to be done to prevent noise-induced hearing loss here and abroad.

And I and others have said before, but it bears repeating: noise-induced hearing loss is 100% preventable. If people avoid noise exposure and protect their ears from noise, they should be able to preserve natural hearing well into old age, rather than needing to rely on assistive hearing devices. The only evidence-based safe noise level remains a 70-decibel time-weighted average for a 24-hour period.

Dr. Fink is a leading noise activist based in the Los Angeles area.  He serves on the board of the American Tinnitus Association, is the interim chair of Quiet Communities’s Health Advisory Council, and the founding chair of The Quiet Coalition, an organization of science, health, and legal professionals concerned about the impacts of noise on health, environment, learning, productivity, and quality of life in America.

Hearing test developed to detect hidden hearing loss

UConn School of Medicine researchers develop first hidden hearing loss hearing test. EurekAlert! reports that “[t]wo researchers at UConn School of Medicine have developed a new hearing test that can identify hearing loss or deficits in some individuals considered to have normal or near-normal hearing in traditional tests.”  Leslie R. Bernstein, professor of neuroscience and surgery at UConn, who conducted the study with Constantine Trahiotis, emeritus professor of neuroscience and surgery, explained the importance of the new test by noting that “acquired hearing loss from excessive noise exposure has long been known to produce significant, and sometimes debilitating, hearing deficits.”  EurekAlert! writes that the “new research suggests that hearing loss may be even more widespread than was once thought,” adding that with this new test, there now is a “validated technique to identify ‘hidden’ hearing deficits that would likely go undetected with traditional audiograms.”

Why do elderly people with otherwise normal hearing have difficulty hearing some conversations?

Background noise to blame for the elderly being unable to keep up with conversations.  The Express reports on a University of Maryland study that found that “adults aged 61-73 with normal hearing scored significantly worse on speech understanding in noisy environments than adults aged 18-30 with normal hearing.”  The study’s authors stated that the “ageing midbrain and cortex is part of ongoing research into the so-called cocktail party problem, or the brain’s ability to focus on and process a particular stream of speech in the middle of a noisy environment.”  Because many older people who are affected by the “cocktail party problem” have normal hearing, the study notes that talking louder doesn’t help.  If an older person can see the person he or she is speaking to, visual cues can help, as well as the obvious–make the environment quieter.

Sadly, many restaurants, bars, and some coffee shops are just too noisy for older people to be able to hear well and participate in conversation.  Organized efforts to push back against unnecessary noise are gaining a toehold in the public sphere, but more needs to be done.  Until things improve, New Yorkers can find some respite by visiting our sister site, Quiet City Maps, for a guide to New York City’s quieter spaces (and a heads-up for places to avoid).

And don’t forget that if a restaurant or coffee shop is too noisy because of loud music, ask them to lower it.  If they don’t, leave and tell them why you won’t be coming back.  Push back starts with your wallet.

Link via @QuietEdinburgh.

Can’t Hear in Noisy Places? There a reason for that:

Melinda Beck, writing for the Wall Street Journal, examines hidden hearing loss, a condition where people have trouble understanding conversations in noisy situations.  Beck looks at how it differs from traditional hearing damage, reporting that:

[T]here’s growing evidence that the causes of problems processing speech amid noise are different than the causes of problems hearing sound. Scientists believe exposure to loud noises can erode the brain’s ability to listen selectively and decode words, without causing traditional hearing damage. Difficulty understanding speech amid noise can set in long before traditional hearing loss.

The researchers at Massachusetts Eye and Ear Infirmary who discovered hidden hearing loss in mice in 2009 have recently shown that damage occurs in humans as well.  “Exactly how such damage, called cochlear synaptopathy, compromises the ability to understand speech amid noise isn’t fully understood,” writes Beck, but “researchers think cochlear synaptopathy may help explain tinnitus, the persistent buzzing or ringing some people hear, as well as hyperacusis, which is an increased sensitivity to unpleasant sounds such as a baby crying or a siren.”

Apparently many people who may have hidden hearing loss also have traditional hearing loss.  Sadly, there isn’t enough information yet for hidden hearing loss to be part of routine diagnosis of hearing problems, but the research continues.  Until then, audiologists suggest patients who have speech-in-noise difficulties consider hearing aids and other assistive listening devices.

Thanks to Charles Shamoon for the link.