For children in the city, how loud is too loud?
Being aware of noise in your child’s environment is important for hearing and cognitive development, studies show. Apps can help identify quiet spaces.
5 years ago
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Thirteen-year-old Theodore has always been a pretty healthy kid — video games, school, recreation. His strongest passions are the violin and classical piano.
But a few months ago, his mother, Marina, found Theodore grabbing at his ears.
“There is a noise in my head, can’t you hear it, can’t you hear it, Mommy?” he said. “Put your head against my head, you will hear it! Take me to the doctor right now!”
That’s how Marina and her husband came to learn that their son had a mild noise-induced hearing loss and that Theodore was experiencing tinnitus. (They asked to be identified only by their first names, to maintain their privacy.)
The family has tried to piece it together. They had gone to a shooting range a couple days before, though there was ear protection. Also, Theodore plays piano and violin a lot. Ultimately, it’s impossible to say what caused the problem.
“It felt like we were walking down the street and the sun was shining and everything was normal and peachy, and then a cyclone came through Philadelphia and lifted my son up … and I could do nothing but stand there at the base of it, screaming,” Marina remembered.
Tinnitus is defined as the perception of sound without an external source present. It’s a biological response that can result from any number of things, from having congestion, to a reaction to certain medications, to an actual loss of hearing due to overexposure to loud noise.
Children are more susceptible to noise than adults. In the same way your voice is louder in a smaller room, sounds are amplified in a child’s ear, said Dr. Frank Wartinger, an audiologist at Children’s Hospital of Philadelphia.
“In general, we humans kind of keep from exposing ourselves to things that are painful because they’re painful, but we don’t think about the kids involved with that,” Wartinger said.
Compared with adults, kids don’t have much say about the noise they’re exposed to, he said.
“If you have a 2-year-old who’s in a noisy situation and they start walking away … they’re going to be told, ‘No, you can’t leave.’ It’s literally not their choice to be in these settings,” Wartinger said.
To understand what exactly is going on inside our ears, Wartinger described the biology of processing sound. To start with, those two floppy things at the sides of our heads don’t actually do that much.
“They filter the sound a little bit, and I think they’re really, really good at holding glasses up, but otherwise they don’t do a whole lot for your hearing,” he said.
After a sound wave reaches the ear, it travels into the ear canal and lands on the eardrum, a thin membrane stretched tight to receive and disperse even the faintest sound.
“I think of it kind of like a trampoline,” Wartinger said. “If you were to throw a golf ball on a trampoline, it’s going to bounce. It doesn’t take a whole lot of weight to make that membrane actually respond and react.”
From there, the sound is amplified eight times, or around 20 decibels, by tiny bones called the ossicles before being sent to the inner ear, known as the cochlea (from the Greek word for snail, because of its coiled shape). This is where things become much more complex, because now it’s time for the brain to process the sound.
Wartinger compared it to a keyboard, “with, let’s say, 30,000 different keys on it, and each key is lined up just to respond to a single note. But you never hear a single note in the world. You hear lots and lots of complexity to the sound that comes into your ear. So very many different parts of that cochlea are actually being played at the same time.”
This is the part of the ear that’s damaged by noise, Wartinger said, as happened in Theodore’s case — “in particular, the little parts of the inner ear called the outer hair cells.”
“You can imagine they’re like little tiny dancers inside your ear that, when they hear their song, they start wiggling and moving, and it’s those wiggles and movements that trigger nerve firings.”
The louder it is, Wartinger said, the harder these hair cells have to wiggle, until they get tired. And if the noise exposure is too loud or lasts too long, he said, the hair cells eventually give up and die.
Unlike other cells in the body, once these cells die, they don’t come back. “They scar over, and you’ve lost that part of your hearing for forever,” Wartinger said.
The day we met, Theodore played — with ear protection in place — a Chopin tune he’d been working on. The ringing in his ears has mostly abated on its own, he said, though there are still some hard days.
His mother said she’s relieved, but “I also am very clear and the doctors and the audiologists and other people told me that … you dodged a bullet.”
Theodore said that, for him, wearing hearing protection has become just as easy as wearing sunglasses.
“If people want to protect their eyes, they should also protect their ears,” he said.
Wartinger agreed, saying, “There’s no reason why any kid or adult really, for that matter, has to develop a noise exposure because of the tools that we have to help.”
In the same way we wear hats or sunscreen to help prevent sunburn, Wartinger said, the same approach can be taken when it comes to noise. The culture needs to change the way it views hearing protection.
“It worked for sunglasses, it worked for sunscreen, it worked for seat belts … for helmets,” he said. “We do all these things without even thinking about it.”