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Listen to a Quartet Sing While You Watch a Close-up of Their Vocal Cords

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The human voice box is a strange and amazing thing. In this video of a quartet singing, you can see the voice box in action via laryngoscope—a tiny camera on a flexible tube inserted through the nose and down the throat.

First, you see the camera enter the nostril and continue over the back of the tongue until you see the larynx. The opening in the center is the entrance to the airway. The whitish bands on either side of the opening are the vocal cords. When they are open, that means the singer is taking a breath. When they are closed, the air is being pushed through them, making them vibrate and create sound. Muscles around the cords adjust the tension on them so they lengthen (making them vibrate faster and produce a higher tone) or shorten (making them vibrate slower and produce a lower tone).

The large flap of cartilage in front of the larynx is the epiglottis. It closes over the larynx when we swallow, so food is shunted back to the esophagus and away from the airway. The process is not failsafe—the human larynx is positioned much lower than it is in other animals, making us vulnerable to choking. But that lower position allows for speech and song, which are enough of an evolutionary advantage to make the risk worth it. We have learned to manipulate this complex machinery to make something not only useful, but beautiful. We pay for it with our own fragility.

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science
What Pop Culture Gets Wrong About Dissociative Identity Disorder
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From the characters in Fight Club to Dr. Jekyll and Mr. Hyde, popular culture is filled with "split" personalities. These dramatic figures might be entertaining, but they're rarely (if ever) scientifically accurate, SciShow Psych's Hank Green explains in the channel's latest video. Most representations contribute to a collective misunderstanding of dissociative identity disorder, or DID, which was once known as multiple personality disorder.

Experts often disagree about DID's diagnostic criteria, what causes it, and in some cases, whether it exists at all. Many, however, agree that people with DID don't have multiple figures living inside their heads, all clamoring to take over their body at a moment's notice. Those with DID do have fragmented personalities, which can cause lapses of memory, psychological distress, and impaired daily function, among other side effects.

Learn more about DID (and what the media gets wrong about mental illness) by watching the video below.

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Food
Hate Red M&M's? You Need a Candy Color-Sorting Machine
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You don’t have to be a demanding rock star to live a life without brown M&M's or purple Skittles—all you need is some engineering know-how and a little bit of free time.

Mechanical engineering student Willem Pennings created a machine that can take small pieces of candy—like M&M's, Skittles, Reese’s Pieces, etc.—and sort them by color into individual piles. All Pennings needs to do is pour the candy into the top funnel; from there, the machine separates the candy—around two pieces per second—and dispenses all of it into smaller bowls at the bottom designated for each variety.

The color identification is performed with an RGB sensor that takes “optical measurements” of candy pieces of equal dimensions. There are limitations, though, as Pennings revealed in a Reddit Q&A: “I wouldn't be able to use this machine for peanut M&M's, since the sizes vary so much.”

The entire building process lasted from May through December 2016, and included the actual conceptualization, 3D printing (which was outsourced), and construction. The entire project was detailed on Pennings’s website and Reddit's DIY page.

With all of the motors, circuitry, and hardware that went into it, Pennings’s machine is likely too ambitious of a task for the average candy aficionado. So until a machine like this hits the open market, you're probably stuck buying bags of single-colored M&M’s in bulk online or sorting all of the candy out yourself the old fashioned way.

To see Pennings’s machine in action, check out the video below:

[h/t Refinery 29]

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