When you think of a middle school science fair, what comes to mind? Perhaps a model of the solar system or a potato clock. One 13-year-old, however, made an exciting discovery. Nora Keegan, a student in Calgary, Canada, claims she noticed children would cover their ears due to hand dryer noise. At 9 years old, she starting testing the volume of the machines in more than 40 public restrooms using a professional decibel meter. Four years later, she confirmed and published her research.
Are Children’s Ears More Sensitive?
While children’s ears are not more delicate than adults, between 3.2% and 17.1% of kids experience hyperacusis — sensitivity to specific sounds. Experts have noticed a higher prevalence of this disorder in children with developmental disabilities, such as autism.
Problematic sounds tend to be those that are loud and unpredictable. Many kids dislike hand dryer noise because it rings out at a high frequency, and you can’t switch it off. Even children with average development can have exaggerated behavioral responses to auditory stimulation.
Companies test hand dryer noise before they release the product to the public. However, this testing doesn’t reveal how loud these items are. Keegan discovered that many machines produce sound greater than 120 decibels, levels that can harm both adults and children.
Many families with sensitive children avoid these devices altogether and use paper towels instead. This choice might be a wise one, as too much exposure to loud sounds can eventually lead to hearing loss.
What Will Scientists Discover Next?
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What Is the Quietest Hand Dryer?
One of the quietest devices tested by Keegan, the GH Wood MT 10 dryer, clocks in at 101 decibels. In comparison, the loudest was the Dyson Airblade, which hits an astounding 121 decibels — louder than a jackhammer.
With just 15 minutes of exposure, these devices are loud enough to cause learning disabilities and rupture eardrums. Luckily, the average person doesn’t spend this much time drying their hands. Still, short-term exposure can worsen hearing and contribute to tinnitus, a ringing in the ears.
In Canada, brands are unable to sell children’s products over 100 decibels. However, they can still install bathroom accessories that are harmful to human health. Keegan’s study shows there’s a need to research the effects of these products.
Dyson and Xlerator, two of the offending manufacturers, claim noise levels well below what Keegan recorded. The young scientist says this is likely due to testing in a controlled lab with sound-dampening walls. Plus, most units are installed at adult levels of height, not accounting for those who are shorter, such as children.
In response to the study, Dyson reached out to Keegan to discuss her research and set up a meeting with an acoustics engineer. Excel Dryer, the company that sells Xlerator hand dryers, made a statement claiming it’s committed to user experience. It says all its high-speed, energy-efficient models come with adjustable sound and speed controls.
What Height Should Hand Dryers Be?
When it comes to hand dryer noise, some devices are quieter than others. However, Keegan claims height is a significant factor, as many devices are louder at a child’s level than an adult’s.
The young scientist measured the sound of hand dryers at the average height of a 3-year-old’s ear, the average height of an adult woman’s ear and the average height of an adult man’s ear. While manufacturers test sound at 18 inches from the wall, Keegan claims children tend to stand much closer.
Another factor to consider is airflow. When your hands enter the stream of air, the decibel levels go up. Keegan discovered this variable accidentally during testing, where she took 20 measurements of each dryer. In fact, every dryer examined hit more than 100 decibels when hands were in the airflow.
Overall, the results point to a substantial, noisy problem. Children who cover their ears when in the presence of a dryer might have the right idea. To avoid harmful sounds, parents can encourage their kids to dry their hands with paper or cloth towels.
Keegan hopes her research will spark a conversation about the issue and lead to better regulation of hand dryers. While manufacturers are taking steps to reduce hand dryer noise, it’s also crucial for governments to pass laws that keep product decibel levels within a safe range.