Horses create special whistle when they whinny and neigh, study finds

A new study found that horses are whistling and vibrating their vocal cords at the same time to create the distinct neigh that accompanies the animal.

The sound of a horse's whinny has long mystified scientists. But a new study suggests the animals pull off a rare vocal trick, creating a signature call by pairing a high-pitched whistle with a low-frequency sound

The research, published Feb. 23 in the Cell Press journal Current Biology, explains how horses produce both sounds at once through a process called biphonation. For anyone who has ever heard neighs or whinnies, here's how they make one of the animal kingdom's most distinctive calls.

When horses whinny, it's making two sounds at the same time: one low and one high. Two sounds are produced: a low-pitched noise and a high-pitched noise. Scientists have long understood the low-pitched sound comes from the horses' vocal cords vibrating, much like when humans talk or sing.

The high-pitched noise, however, has been more difficult to explain as researchers weren't quite sure where it came from.

The study, which took a closer look at the horses' vocal anatomy and running acoustic experiments made a surprising discovery: the high sound wasn't made by vibrating vocal cords but a whistle.