Why a Dripping Faucet Makes That Maddening 'Plink' Sound—and How to Stop It

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iStock

In most cases, calling a professional is the best option when dealing with a stubborn faucet leak. With the right tools and knowledge, the problem isn't that difficult to solve. But when every other thought you have is interrupted by that incessant "plink" noise, even a few hours spent waiting for the plumber can feel like an eternity. A team of scientists recently looked at the mechanics that make that sound so annoying, and they've come up with a quick fix you can use to silence it before tackling the source.

The researchers from the University of Cambridge recently published their findings in the journal Scientific Reports. To get to the bottom of the annoying acoustics, they recorded a leaky faucet using a microphone, a hydrophone, and ultra-high-speed cameras. “A lot of work has been done on the physical mechanics of a dripping tap, but not very much has been done on the sound,” lead researcher Anurag Agarwal said in a press release. “But thanks to modern video and audio technology, we can finally find out exactly where the sound is coming from, which may help us to stop it.”

They found that the unmistakable "plink" comes not from the water droplet itself, but from an air bubble trapped beneath it. When a drop of water hits something, a cavity forms inside it. This cavity immediately recoils, creating a water column that splashes away from the surface that was hit. The cavity recoils so quickly that it leaves a small air bubble beneath the water.

Scientists already knew the physics, but until now it was unclear which part of the equation produces the dripping noise. The University of Cambridge team observed that it's not the impact of the droplet, the creation of the cavity, or the upward splash of water that make the sound: It's the air bubble, which vibrates and pushes sound waves through the air in a way that's uniquely grating to the ears.

The researchers were also able to identify a way to neutralize this effect without any fancy equipment. Just add some liquid soap to the bottom of the sink to change the surface tension of the water each time a droplet splashes. This slight adjustment is enough to stop the air bubble from forming and quiet the sound.

The constant noise keeping you up at all hours of the night isn't the only reason leaky taps are a pain. According to the Environmental Protection Agency, Americans lose 1 trillion gallons of water a year to leaks. Every year, the EPA runs Fix a Leak Week, a campaign aimed at getting homeowners to catch all the wasteful leaks on their property—not just the ones within hearing distance.

Bombshell, Victoria’s Secret’s Bestselling Fragrance, Also Happens to Repel Mosquitoes

Dids, Pexels
Dids, Pexels

People love Bombshell, the best-selling fragrance at Victoria’s Secret, for its summery blend of fruity and floral notes. Not everyone is a huge fan, though: As Quartz reports, the perfume is surprisingly good at warding off mosquitoes. In fact, it’s almost as effective as DEET insect repellent, according to the results of a 2014 experiment by researchers at New Mexico State University.

Researchers took 10 products that are commercially available and tested their ability to repel two different species of mosquitoes: the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus), both of which are known to transmit diseases like dengue fever, chikungunya, and yellow fever. In doing so, volunteers subjected their own flesh to the test by placing their hands on either side of a Y-shaped tube containing the blood-sucking critters. One hand was covered in a synthetic rubber glove, while the other hand was sprayed with one of the products but otherwise left bare. Researchers recorded which tunnel the mosquitoes flew to, and how long they avoided the other end.

Three of the products contained DEET, while four products didn’t. In addition, there were two fragrances (including Bombshell) and one vitamin B1 skin patch. The DEET products were the most effective, but Bombshell proved to be nearly as good, keeping mosquitoes at bay for roughly two hours.

“There was some previous literature that said fruity, floral scents attracted mosquitoes, and to not wear those,” Stacy Rodriquez, one of the study’s authors, said in a statement. “It was interesting to see that the mosquitoes weren’t actually attracted to the person that was wearing the Victoria’s Secret perfume—they were repelled by it.”

This isn’t the first time a perfume has had an unintended effect on the natural world. It turns out that tigers are obsessed with Calvin Klein’s Obsession for Men cologne, partly because it contains a synthetic version of civetone, a pheromone that's secreted by glands located near a civet’s anus. This substance was once used to create musky fragrances, but nowadays the scent is mostly reproduced in a lab. Still, the fake stuff must be pretty convincing, because big cats go crazy when they catch a whiff of it.

[h/t Quartz]

Mystery Solved: Scientists Have Figured Out Why Some Squirrels Are Black

Rena-Marie/iStock via Getty Images
Rena-Marie/iStock via Getty Images

It can be something of a surprise to see an animal sporting a fresh coat of paint. Blue lobsters occasionally surface after being caught in traps. A pink dolphin was spotted in Louisiana in 2007 (and several times since). In the Chinese province of Shaanxi, a cute brown and white panda greets zoo visitors.

Another anomalous animal has joined their ranks. Black squirrels have been spotted in both the United States and the UK, and now scientists believe they know why.

Like many animals with unusual color schemes, black squirrels are the result of a genetic detour. Researchers at Anglia Ruskin University, Cambridge University, and the Virginia Museum of Natural History collaborated on a project that tested squirrel DNA. Their findings, which were published in BMC Evolutionary Biology, demonstrated that the black squirrel is the product of interspecies breeding between the common gray squirrel and the fox squirrel. The black squirrel is actually a gray squirrel with a faulty pigment gene carried over from the fox squirrel that turns their fur a darker shade. (Some fox squirrels, which are usually reddish-brown, are also black.)

A black squirrel is pictured
sanches12/iStock via Getty Images

Scientists theorize a black fox squirrel may have joined in on a mating chase involving gray squirrels and got busy with a female. The black fur may offer benefits in colder regions, with squirrels able to absorb and retain more heat, giving them a slight evolutionary edge.

In North America, black squirrels are uncommon, with one estimate putting them at a rate of one in every 10,000 squirrels. In 1961, students at Kent State University in Ohio released 10 black squirrels that had been captured by Canadian wildlife authorities. The squirrels now populate the campus and have become the school’s unofficial mascot. Their coloring might help them hide from predators, which might come in handy at Kent State: The campus is also home to hawks.

[h/t The Guardian]

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