When a horse whinnies, there's more than meets the ear

Horses, like the Norwegian fjord breed apparently yawning in this image, generate both a high frequency and a low frequency when they whinny.

A new study finds that horse whinnies are made of both a high and a low frequency, generated by different parts of the vocal tract. The two-tone sound may help horses convey more complex information.

(Image credit: ullstein bild)