Pigs grunt, bark and squeal to communicate with each other, indicating happiness, fear and other emotions. The bulk of their communication is verbal with approximately 20 distinct sounds.
The most common noise that a pig makes is the grunt. In English, the noise is rendered as "oink," but in French it's "groin groin" and in Polish "chrum chrum." The word "oink" is an example of onomatopoeia.
A pig grunts as a general response to familiar noises or while rooting for food. The length of the grunt indicates different meanings, with short grunts conveying excitement and long grunts forming either a contact call or expressing happiness. Squealing or screaming occurs when a pig is agitated or hurt. Larger, more dominant pigs have been heard barking at smaller, submissive ones to threaten them.
Pigs can also communicate with each other through scent. Researchers theorize that scent and vocals are higher prioritized than vision in pigs when witnessing a group of blindfolded pigs sort themselves into a hierarchy. A pig's tail also conveys a great deal of information about its health and well-being. A healthy pig has a tightly curled tail, while an ill one might allow its tail to twitch in distress. However, farms often clip a pig's tail, eliminating this method.