Donkeys make a sound called braying. The onomatopoeias for brays are "hee-haw" and "eeyore." The latter is so common that Winnie the Pooh's donkey friend is named Eeyore.
Donkeys have loud voices to keep in contact with their herds. The bray's pitch signals what the donkey wants to communicate. Donkeys respond to other donkeys braying in distress and to music, such as that of a violin. Some donkeys are more vocal than others and bray more frequently. Braying is most often used to signal distress, so donkey owners should be concerned if their donkeys constantly bray. Mules, which are hybrids of horses and donkeys, make similar sounds to donkeys.