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Why Your Brain Sometimes Hears Sounds That Don't Exist

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iStock

In May 2018, the internet was abuzz with debate: Laurel or Yanny? Some listeners heard the former name in the viral audio clip, while others were convinced the voice was saying the latter. AsapSCIENCE’s latest video, spotted by Digg, helps explain how aural illusions work, and why hearing isn't quite as cut-and-dried as you might think.

As it turns out, it's relatively easy to trick the brain into hearing a sound that doesn't exist. Hearing is all about perception, and expectation plays a huge role. Your brain uses context to interpret the signals it receives from the sound waves that hit your ear. Research has found that when you expect to hear sound, the brain’s auditory cortex is activated in the same way as when you’re actually hearing sound.

The brain often fills in gaps where it thinks sound should exist, as the examples in the video show. This, AsapSCIENCE explains, is called “temporal induction.” That might mean hearing the words to Smash Mouth’s “All Star” when only a piano melody is playing, if you already know what the words should be. It might mean seeing a word written onscreen and hearing the full word in the audio track, even when part of the audio cuts out a syllable. Or it could mean hearing sound in a completely silent GIF, as many people do when they watch an image of a power line bouncing up and down.

Intrigued? Learn more in the video below, and then test your hearing on these other aural illusions.

[h/t Digg]

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MARS Bioimaging
The World's First Full-Color 3D X-Rays Have Arrived
MARS Bioimaging
MARS Bioimaging

The days of drab black-and-white, 2D X-rays may finally be over. Now, if you want to see what your broken ankle looks like in all its full-color, 3D glory, you can do so thanks to new body-scanning technology. The machine, spotted by BGR, comes courtesy of New Zealand-based manufacturer MARS Bioimaging.

It’s called the MARS large bore spectral scanner, and it uses spectral molecular imaging (SMI) to produce images that are fully colorized and in 3D. While visually appealing, the technology isn’t just about aesthetics—it could help doctors identify issues more accurately and provide better care.

Its pixel detectors, called “Medipix” chips, allow the machine to identify colors and distinguish between materials that look the same on regular CT scans, like calcium, iodine, and gold, Buzzfeed reports. Bone, fat, and water are also differentiated by color, and it can detect details as small as a strand of hair.

“It gives you a lot more information, and that’s very useful for medical imaging. It enables you to do a lot of diagnosis you can’t do otherwise,” Phil Butler, the founder/CEO of MARS Bioimaging and a physicist at the University of Canterbury, says in a video. “When you [have] a black-and-white camera photographing a tree with its leaves, you can’t tell whether the leaves are healthy or not. But if you’ve got a color camera, you can see whether they’re healthy leaves or diseased.”

The images are even more impressive in motion. This rotating image of an ankle shows "lipid-like" materials (like cartilage and skin) in beige, and soft tissue and muscle in red.

The technology took roughly a decade to develop. However, MARS is still working on scaling up production, so it may be some time before the machine is available commercially.

[h/t BGR]

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ESA/Herschel/SPIRE; M. W. L. Smith et al 2017
Look Closely—Every Point of Light in This Image Is a Galaxy
ESA/Herschel/SPIRE; M. W. L. Smith et al 2017
ESA/Herschel/SPIRE; M. W. L. Smith et al 2017

Even if you stare closely at this seemingly grainy image, you might not be able to tell there’s anything to it besides visual noise. But it's not static—it's a sliver of the distant universe, and every little pinprick of light is a galaxy.

As Gizmodo reports, the image was produced by the European Space Agency’s Herschel Space Observatory, a space-based infrared telescope that was launched into orbit in 2009 and was decommissioned in 2013. Created by Herschel’s Spectral and Photometric Imaging Receiver (SPIRE) and Photodetector Array Camera and Spectrometer (PACS), it looks out from our galaxy toward the North Galactic Pole, a point that lies perpendicular to the Milky Way's spiral near the constellation Coma Berenices.

A close-up of a view of distant galaxies taken by the Herschel Space Observatory
ESA/Herschel/SPIRE; M. W. L. Smith et al 2017

Each point of light comes from the heat of dust grains between different stars in a galaxy. These areas of dust gave off this radiation billions of years before reaching Herschel. Around 1000 of those pins of light belong to galaxies in the Coma Cluster (named for Coma Berenices), one of the densest clusters of galaxies in the known universe.

The longer you look at it, the smaller you’ll feel.

[h/t Gizmodo]

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