Scientists discover bizarre 'organ' in koalas

How are koalas, not known for their large size, emit such deep bellowing sounds? Researchers have spotted an extra set of vocal folds outside the larynx that lets them do so.

Simple calculations suggest koalas should have high-pitched voices. That's because the pitch generated by an object is linked to its size, and usually animals' vocal chords tend to be large or small according to the mass of their bodies.

But koalas have relatively low voices, especially males, which produce bellowing sounds during the mating season that alternately sound like a donkey braying and a frog vomiting.  The average pitch of this bellow is 20 times lower than an animal that weighs 8 kilograms (18 lbs.) and more typical of an animal the size of an elephant, according to a study published today (Dec. 2) in the journal Current Biology.

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Original Source: http://www.csmonitor.com/Science/2013/1202/Scientists-discover-bizarre-organ-in-koalas