We see them everywhere. They’re in restaurants, coffee shops, bookstores, department stores and city parks — kids staring downward, lost in their cell phone or other electronic gadget, with earbuds jammed in their ears, completely oblivious to the world around them. Many times, the music they’re playing on their phone or MP3 player is so loud, an observer can hear it from several feet away. While much research has examined how the overuse of technology affects child brain development, new concern is rising regarding the risks children face for premature hearing loss, particularly when using earbuds with their technology.
According to the Centers for Disease Control and Prevention, since the dawn of the MP3 player back in 2001, 13% of American children between ages 6 and 19 have acquired some level of noise-induced hearing loss. That’s more than 5 million young people. According to audiologists today, hearing loss in teens is about 30% higher now than it was in the 1980’s and 1990’s. While teens have always gone to rock concerts, which pose a great threat to premature hearing loss, the significant increase in today’s generation of younger people is being attributed to the daily use of earbuds with their cell phones and MP3 players.
25 years ago, people used their Walkman for about ½ hour per day, either while jogging, working out, or doing some other temporary activity. When the activity was finished, so was their listening time. They were also using headphones that went over the ears. Back then, it wasn’t as common to turn the volume up too high because the simpler technology couldn’t handle the output, and the sound would become distorted. At the same time, these devices ran on two AA carbon batteries with limited lifespans, so using them for hours on end wasn’t an option.
Today, cell phones and MP3 players can last for years and have batteries that are rechargeable. Because cell phones are also computers, kids can listen to music or watch videos for hours on end while using earbuds that are actually inserted into the ear canal, most often just ½ inch from the eardrum. The digital technology makes sound crystal clear, so there is no real incentive to keep it low. In fact, kids have a strong tendency to turn the volume up to drown out exterior noise from things like crowds and traffic.
With earbuds being so close to the hearing mechanism inside the ear, the risk for hearing damage is very real. Just by placing the source of sound closer to the eardrum, earbuds have been shown to increase volume by 9 decibels when compared to other hearing appliances.
Based on the increase in patients audiologists are seeing, it’s been estimated that anywhere between 15% and 25% of children listen to their devices at hazardous levels.
How Hearing Happens
The cochlea or small snail-shaped inner ear chamber is where hearing happens. It’s lined with 16,000 tiny hair cells that vibrate at different frequencies. It’s those vibrations that get translated into nerve signals and sound perceptions. We know that loud noise damages and even kills these fragile hair cells and once gone, they never regenerate. Hearing loss is cumulative over a lifetime, and any amount of hearing loss is irreversible. Because it comes on gradually, many people don’t notice it until they’re in their 40’s or 50’s, often experiencing the kind of hearing loss that isn’t normally seen until the 70’s.
New research from Harvard Medical School’s Eaton Peabody Laboratory is now showing that the nerve synapses in the inner ear are actually more vulnerable to damage than the hair cells themselves.
A series of experiments with young animals showed that even a single exposure to loud noise accelerates hearing loss later in life.
This is mostly due to damage done to nerve synapses. In fact, a person can lose up to 90% of their cochlear hair cells and still be able to detect a tone in a quiet room. However, once background noise is introduced, hearing ability drops dramatically. So while a person’s hair cells may be largely intact, they can still experience hearing loss if the nerve synapses are damaged. When a nerve fiber is damaged, it never reconnects or responds to sounds. Within a few months or years, the neuron itself shrivels and disappears. Earbuds are of particular concern because they deliver stronger, more damaging sound waves straight to the cochlea, even at lower volumes.
Typical signs of hearing loss include ringing, roaring, hissing or buzzing sounds in the ear, difficulty understanding speech in noisy places or locations with poor acoustics, muffled sounds or a feeling of fullness in the ear, and listening to radio or TV at higher levels than in the past. Anyone experiencing these kinds of symptoms should be examined by a professional.
How Loud is Too Loud?
According to the National Institutes of Health, long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. To put this into perspective, normal speech registers at about 60 decibels. City traffic can reach 85 decibels, as does movie theater volume, although it has peaks that are much higher. A lawnmower registers at 90 decibels, a chainsaw at 100, and a rock concert or stadium noise range from 110-120. Most MP3 players today can produce volumes up to 120 decibels. At that level, permanent hearing loss can occur in as little as 8 minutes. The louder the noise, the shorter amount of exposure is required to create permanent hearing loss.
Anything under 75 decibels is considered healthy. By contrast, a noisy lunchroom full of screaming middle schoolers averages about 89 decibels. There’s a reason why teachers keep telling children to quiet down during lunchtime, and it’s not because they’re boring adults who don’t know how to have fun. This is about the same level of noise an MP3 player produces at just 70% of volume.
Setting Healthy Levels
The most effective way to preserve hearing is to stop using earbuds completely because they place sound too close to the inner ear. Stop using headphones, as well. If you must use headphones, choose the highest quality you can find and be sure they fit completely over the ear so there is little temptation to turn up the volume.
If someone can hear “leakage” from your headphones from several feet away, the volume is too loud.
Likewise, if you can’t hear anything going on in the environment around you with your headphones on, the sound level is too high. Many cell phones and MP3 players have the ability to lock sound at lower levels. This can be a great tool to train yourself to get accustomed to lower levels and prevent children from getting in the habit of turning the volume up all the time. Regardless of where you are or what you’re doing, the general sound rule is that if you have to raise your voice to be heard, it’s too loud.
When using headphones, most doctors and audiologists recommend following the 60/60 rule. Headphone usage should be limited to 60 minutes per day at 60% of the maximum volume or less. Just by making these simple changes, you’ll be able to preserve hearing for you and your child for a lifetime.
For more health insights from Dr. Sadeghi, please visit Behiveofhealing.com to sign up for the monthly newsletter or check out his annual health and well-being journal, MegaZEN here. For daily messages of encouragement and humor, follow him on Twitter at Behiveofhealing.