Newly Discovered Organ Helps Koalas Bellow At Elephant Pitch
by Ed Yong
Koalas may look cute and placid but come the mating season, the males produce a bellow that… well… is not the sound you expect them to make. As they inhale, they sound like a loud, creaky door. As they exhale, they sound like someone belching vigorously. Put these together, and you get a continuous racket that sounds like an angry Wookiee.
The bellows are surprising to passers-by, but they perplex scientists too. Koalas just shouldn’t be able to make a sound that low.
Mammals make calls using an organ in our throats called the larynx, or voicebox. When air passes through the larynx, it vibrates a pair of membranes called the vocal folds (or vocal cords). These create sound waves in our nose and mouth. We can control the pitch of those waves by using muscles in the larynx to change the tension in the vocal cords. The size of the cords also matters—it sets the lowest possible noise that we can make. This is why small mammals can only manage high-pitched squeaks, while big species can produce rumbling bass…