Why Do Shells Sound Like the Ocean?

iStock
iStock

Kevin in Bentonville, Arkansas, wrote in to ask this question: "Why do you hear the ocean when you put a seashell up to your ear?"

All right, first things first: no matter how much it may sound like the rolling waves, it's not actually the ocean you're hearing in a shell.

Now that we've got that out of the way, what exactly is it that you're hearing? In a word, noise; the ambient noise that's being produced all around and inside you, which you normally don't hear or pay attention to because it's too quiet.

To amplify this noise so you can hear it clearly, you need a resonator. Want to make one on the cheap? Form an O shape with your mouth and flick your finger against your throat or cheek. You should hear a note. Make a smaller or larger O, or change the shape of your mouth, and you'll get different notes. Sort of like this. What you're doing here is letting your mouth fulfill its potential as a Helmholtz resonator, where sound is produced by air vibrating in a cavity with one opening. Different pitches can be coaxed out by changing the shape of the resonating cavity.

The seashell you're listening to—the inside of which has many hard, curved surfaces great for reflecting sound—is essentially doing the same thing you just did with your mouth. The ambient noise mentioned before—the air moving past and within the shell, the blood flowing through your head, the conversation going on in the next room—is resonating inside the cavity of the shell, being amplified and becoming clear enough for us to notice. Just like the various shapes we make with our mouths will produce different pitches, different sizes and shapes of shell sound different because different resonant chambers will amplify different frequencies.

The fact that all shells sound just a little bit like the ocean is purely coincidental. Holding any sort of Helmholtz resonator to your ear will produce a similar effect, whether that object is associated with the ocean or not. Put an empty glass over your ear or even cup your hand over it, and the sound you hear will be just about the same.

The Real Reason Costco Employees Check Receipts at Exits

Tim Boyle, Getty Images
Tim Boyle, Getty Images

If shoppers have one complaint about Costco—the vast discount warehouse chain with a notoriously permissive return policy and speedy checkout lanes—it’s that the employees posted at the exits to take a marker to customers' receipts seem vaguely insulting. Is the premise that everyone is a shoplifter until proven otherwise?

Not exactly. A recent rundown of Costco's policy from The Takeout (via Cheat Sheet) points out that the true motivation of these exit-door sentries isn’t to identify potential thieves. It’s to make sure that Costco isn’t picking the pockets of its customers.

According to employees who have made not-for-attribution comments, Costco is actually examining receipts to make sure a shopper hasn’t been overcharged for their purchases. Someone with three giant bundles of toilet paper in their cart, for example, might have been charged for four. By giving the receipt a cursory glance, the employee can make sure a cashier didn’t inadvertently ring up phantom crates of canned tuna.

Of course, if someone did try to wheel out several big-screen televisions without a receipt, the exit door employee would likely make an issue of it. But they’re not in loss prevention, and the measure isn’t intended to deter thieves. If you do have something in your cart you didn’t pay for, their immediate assumption is that the mistake is almost certainly the result of a cashier not scanning the item.

In fact, hardly any criminals are caught at the door—which isn't to say the store isn't immune to theft. Earlier this year, thieves at a Seattle Costco were busted with armloads of laptops after they barged out of the back entrance. In June, a Costco in Alpharetta, Georgia, was victimized by burglars who smashed the jewelry case at night and made off with $10,000 worth of valuables.

[h/t The Takeout]

If the Polls Close While You’re Still in Line to Vote, Don’t Leave

iStock/fstop123
iStock/fstop123

If the Twitter photos of lines snaking around city blocks are any indication, people are showing up to vote in today's midterm elections in droves. And while the high voter turnout is a great example of democracy in action, it spells bad news for voter wait times. So, what do you do if you’re stuck at the back of the line when your polling place closes? You stay right where you are.

If you didn't take advantage of your state's voting time-off laws to cast your ballot during the workday (if your state has them, that is), there's a good chance you'll be caught in an after-work crush. But don't despair! As long as you are in line at closing time, you have a legal right to vote—so don’t let anyone tell you otherwise. In fact, if someone does attempt to force you to leave, you are encouraged to call a voter protection hotline (such as 1-866-OUR-VOTE) or submit a complaint to the Department of Justice (1-800-253-3931).

These hotlines are also available to help you if you witness acts of voter intimidation or discrimination. As they say: If you see something, say something!

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