Every day for the past four years, dozens of people have posted in the comments of a particular YouTube channel expressing their love and appreciation for its content. The content: two minutes and six seconds of deep, quiet humming that will make your phone vibrate on the table, accompanied by a slightly trippy animation of swirling stained glass.

It’s not a good video. But it’s not supposed to be. It’s called “Sound to Remove Water from Phone Speaker (GUARANTEED).” There are many others like it. And the comments – “the community,” as many there call it – are almost all from people whose phones have gotten wet in one way or another. “Walked through a river with my phone in my pocket,” says one recent one. “Yes, the steam from the shower is why I’m here,” says another. “I’ve used my phone in the shower, this is a lifesaver.” And so it goes, many of them from repeat offenders. “This is our third time back this month.” “It’s been three weeks and I’m back.” “Dropped my stuff in the shower AGAIN!”

For more on our wet phone mystery (and the future of AR headsets), visit this episode of The Vergecast.

If the comments are to be believed, about half of the video’s 45 million views are from people taking their phones into the shower or bath, trusting that they can play this video and everything will be fine. I first experienced this earlier this year when my nephew’s phone slipped out of his pocket and fell into a river near our Airbnb in a small town in Virginia. Miraculously, we found his phone, brought it inside, and tried to dry it off. A moment later, one of his friends casually suggested we play “one of those videos that gets the water out.” We put in “Sound to remove water from phone speaker (GUARANTEED)” and eventually the phone was fine.

Since then, I’ve been trying to figure out if these videos really work. Are all these happy shower scrollers just the beneficiaries of phones that have become much more waterproof and rugged in recent years? Or should we stop recommending rice and instead recommend “Sound to remove water from phone speaker (GUARANTEED)”?

The first thing I did was ask the phone manufacturers what they thought. No one at Apple, Google, or Samsung offered a more interesting answer than a link to a general support page asking “What to do if your phone gets wet?”, but a few other people I spoke to said the theory seemed plausible to them.

The theory goes like this: A speaker is really just displacing air, and if you can get it to displace enough air with enough force, you might be able to push droplets of liquid out of the air. “The lowest note the speaker can play, the highest volume it can play,” says Eric Freeman, senior research director at Bose. “That creates the most air movement pushing on the water trapped in the phone.” Generally speaking, the bigger the speaker, the louder and deeper it can get. Phone speakers tend to be tiny. “So in the YouTube videos,” says Freeman, “it’s not really deep bass. But it’s in the lower range that a phone can make sound.”

The best real-world example of how this can work is probably the Apple Watch, which has a special feature to drain water when it gets wet. When I first contacted iFixit to ask about my water-ejection conundrum, Carsten Frauenheim, a repair engineer at the company, said the watch works on the same theory as in the videos. “It’s just a certain oscillating sound that pushes the water out of the speaker grilles,” he said. “I’m not sure how effective the third-party phone versions are, because they’re probably not optimally tuned. We could test it.”

The company actually did conduct tests. Shahram Mokhtari, iFixit’s lead teardown engineer, and Chayton Ritter, an engineering student who also works on iFixit’s editorial staff, took four phones and got them wet. We chose an iPhone 13, a Pixel 7 Pro, a Pixel 3, and a Nokia 7.1, all of which we chose not based on science but because I had these devices on hand and was willing to destroy them in the name of science. Each phone went into a UV bath for about a minute, after which Ritter took it out, tapped it to get some water out, played one of the water-ejection videos, and left it out overnight. The next day, he checked where there was still residue of the UV dye, an indication that liquid had gotten in and wasn’t coming out.

The results varied widely. The Pixel 7 Pro was practically bone dry, the Nokia 7.1 was more or less ruined, and the iPhone 13 and Pixel 3 were somewhere in between. But these aren’t perfectly controlled tests, as Mokhtari pointed out: A phone’s seal can change over time or become damaged in unnoticeable ways. He and Ritter both said emphatically that no matter what your phone maker touts or what you’ve experienced before, getting your phone wet is always a risk. And it gets riskier over time.

As for what the YouTube video did, however, the evidence was pretty clear. It works! A little bit. While playing the video on each phone, Ritter also took close-up shots of the speaker on each phone, and in each case, the phone immediately shot out a torrent of drops. The effect didn’t last long, but it was clearly expelling water that wouldn’t have come out otherwise.

The videos weren’t a complete solution to the problem, though. A smartphone’s speaker seems to be powerful enough to push air out right next to the speaker, but not enough to solve problems elsewhere on the device — particularly under the buttons, USB port or SIM card slot, the other most common entry points. And if the liquid didn’t come out with the first gush, Ritter found that the drops usually just sloshed back and forth when the speaker was moved. So, he says, “I’m saying (the videos) kind of work. It can’t hurt, but I don’t see it as an ultimate solution or a way to get all the liquid out.”

That might be why companies like Apple and Samsung don’t offer water resistance as a feature on their phones, but do on their smartwatches. “The watches have fewer cavities and holes than the phones, so they can push the water out of those cavities,” says Mokhtari. “With the phones, the speakers are on the top and bottom, so you can’t get to cavities like the SIM card slot. It’s just not possible to push water out of those cavities.”

The good news for anyone who watches in the shower: Phones are getting more and more waterproof: Three of the four phones Ritter tested still worked perfectly, and the most recent of these, the Pixel 7 Pro, showed no liquid at all. The bad news is that there’s no guarantee they’ll stay waterproof forever. And the really bad news is that you’re tempting fate even more if you shower with your phone. “I don’t know what else is in shampoo,” Ritter says, “but it’s probably more conductive—very rarely does perfectly fresh water get into your iPhone.”

So, be sure to bookmark a water ejection video and download it for emergency use. Join the Sound for Removing Water from Phone Speaker (GUARANTEED) community where everyone seems to cheer on each other for their device’s survival. But don’t put too much faith in it. Everyone I spoke to ended up giving me the same advice: just don’t leave your phone in the shower.