For many potential entrée animals this [sound of lion roar] is one of the scariest sounds around. Scientists long thought the lion’s distinctive roar was due to thick layers of fat inside the vocal cords. But new research suggests that it's not the fat that makes the roar, it's the shape of the vocal cords themselves.

Most animals have triangular vocal cords. But the lion's mighty pipes are square. Tigers’ too. That square shape allows the tissue to withstand more stretching, which lets the big cats create louder roars using lower lung pressure. The finding is the journal Public Library of Science ONE. [Sarah Klemuk et al., "Adapted to Roar: Functional Morphology of Tiger and Lion Vocal Folds"]

When we say loud, we mean loud. Lion roars can travel over five miles, and reach up to 114 decibels, which is as loud as a jet airplane taking off. The researchers suggest that the fat is there to cushion the cords, and to provide tissue for repair if the cords get damaged.

Understanding how that repair happens might help doctors fix damaged vocal cords in humans, too. Which would have to be called a roaring success.

—Rose Eveleth

[The above text is a transcript of this podcast.]