The Loh Down On Science

Koala vocal cords produce unexpected chords!

Charlton et al., Curr. Biol., 2013

(A) The velar vocal folds (VVFs, red) are located at the intersection between the oral and nasal portions of the pharynx just opposite to the laryngeal entrance. Oral tract in light blue, nasal tract in yellow, soft palate in light red, laryngeal vocal folds in green, arytenoid cartilage in blue.

Have you ever heard a koala bellow? 

This is Sandra Tsing Loh with the Loh Down on Science.

Koalas should sound cute, right? Instead, imagine the longest, lowest frat brother belch. Listen: [sound]  That’s a male koala’s mating sound.

This has baffled scientists. Males weigh about 17 pounds. They have small vocal cords. But their bellows are 20 times lower than their vocal cords should be able to produce.  A sound more matched to elephants!  How do they do it?

Biologists at Britain’s University of Sussex dissected male koala specimens.  They found something that noone had ever noticed before:  Where the throat meets the nasal passage, there was an opening that led to a second set of vocal cords.  And not just cute little koala-sized cords.  These were heavily folded.  In fact 600 times heavier than the main cords.  Enough to produce low bellows.

To test this, the biologists repeatedly blew air through the dissected cords.  Ew.  But this confirmed that the cords could produce the bellow.

For many more surprising tones.  Down Under.

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The Loh Down on Science is produced by LDOS Media Lab, in partnership with the University of California, Irvine, and 89.3 KPCC. And made possible by the generous support of the Gordon and Betty Moore Foundation.


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