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April 12th, 2017

I can’t understand what you’re saying: The problem of ‘hidden’ hearing loss

By davidolmos

When choosing a new restaurant to visit, one of my biggest considerations after the quality of the food and location is this: how noisy is it? Having lived since childhood with a significant hearing loss in one ear, I try to avoid loud restaurants where I’ll likely have to struggle to hear and understand what the person across the table is saying. It’s stressful, frustrating, even embarrassing.

I’ve got plenty of company in this regard. About 15 percent, or 37.5 million, U.S. adults report some trouble hearing, according to federal data. And the problem is growing, with an estimated 1.1 billion teenagers and young adults at risk of hearing problems due to exposure from unsafe levels of sound from smartphones, other audio devices and loud entertainment venues, a 2015 report from the World Health Organization found.

Recently, much attention has focused on the issue of “hidden” hearing loss, a type of hearing deficit that often doesn’t show up in standard hearing tests in the doctor’s office, says Alison Grimes, director of audiology and newborn hearing screening at UCLA Health. People with hidden hearing loss may have a “normal” hearing test, yet they are aware that they are having considerable difficulty understanding speech in noisy environments.

“One of the difficult things about hidden hearing loss is that it doesn’t show up on those typical hearing tests,” says Grimes. “People with hidden hearing loss will be able to detect soft sounds—that is, pure sounds like the notes on a piano, a fairly simple measure of hearing. But their classic complaint is “I hear but I don’t understand.’ ”

Hearing loss is thought to be caused by damage to different types of hair cells in the inner ear that respond to sound. Damage to the fibers in the auditory nerves that connect to hair calls can make it difficult to hear in noisy environments. Often an audiogram, the most common type of hearing test, conducted in a quiet room, does not pick up this type of hearing loss, meaning patients can “pass” the test even if the fibers are damaged.

In the recent past, patients who visited their doctor with concerns about their hearing were often told their hearing was fine, Grimes says.

“We have seen these patients forever and we used to tell them, “There’s nothing we can do for you’ “, she says. “Now we really know that their hearing is not completely normal. It’s just that we haven’t had the tools to measure that it’s not normal, but we’re developing those tools.”

If a patient with hearing complaint tests normal on a standard test, audiologists can do a special exam to measure hearing using specialized speech perception tests in a background noise, Grimes says. “Basically, we have to perform specialized speech tests to discover certain speech sounds that they cannot hear or discriminate. For instance, if we say the word “fat” these patient may interpret the word as “sat.”

With new research into how hearing is damaged both by aging and exposure to load sounds, the estimates of nearly 40 million Americans with hearing loss may be too low, says Grimes.

“The actual prevalence of hearing loss is much greater and begins to start at a much younger age,” she says.

Studies have shown that hearing loss is becoming more prevalent in teenagers, says Grimes. From traffic noise to earbuds blasting music and high-decibel entertainment at sporting events and music concerts, young people (and adults) are exposed more often to louder sounds. While hearing loss can be caused by several factors, such as genetics and congenital conditions, the biggest preventable cause of damaged hearing is noise, Grimes says.

“I went to a (Bruce) Springsteen concert last year and wore ear protection,” Grimes says. “At one point I took out my earplug because I wanted to hear what he was saying and after I took it out the noise was so loud I thought I would die.”

Because our environment has become noisier, Grimes recommends that people get their first hearing test when they suspect hearing loss or at age 40. Previously, the common recommendation was for a hearing test at age 50, she says.

While there are no good treatments specifically for hidden hearing loss, Grimes believes that may change with more research.

“Any treatment that would happen would be very delicate unless it could be treated with a drug or an injection,” she says. “Right now we’re more in the discovery phase, not the treatment phase.”

Meantime, people who suspect some hidden hearing loss may want to limit their time in loud places.

“Restaurants consider a noisy atmosphere to be a sign of a successful restaurant,” she says. “But the No. 1 complaint of my patients is hearing in a restaurant.”

Tags: audiogram, audiology, concert, Dr. Alison Grimes, ear, ear problems, earplug, hearing, hearing aid, hearing loss, hearing test, loud sounds, newborn hearinf screening, News & Insights, sound, ucla audiology

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