The fuzzy koala sure is cute. Until it opens its mouth. [Sound of koala vocalization.] The mating call of a male koala has roughly the same pitch as an elephant's trumpet. How does this tiny mammal produce such a low voice?
Back in 2011, as a previous 60-Second Science explained, researcher Benjamin Charlton of the University of Sussex suspected the position of the voice box was responsible. Now, Charlton and his team have discovered an entirely new organ may be the source.
In most mammals, sound is produced when air passes through the voice box and vibrates its inner membranes, called vocal folds. But male koalas have an extra set of vocal folds, located in their throats but outside their voice boxes. These velar vocal folds are three times longer than the pair in the voice box and weigh 683 times more. The work is published in Current Biology. [Benjamin D. Charlton et al., Koalas use a novel vocal organ to produce unusually low-pitched mating calls]
Large and heavy velar vocal folds let male koalas bellow at low frequencies. So they can draw in lady koalas, who think a low voice is highly attractive.
[The above text is a transcript of this podcast.]