As fans of The Far Side have long suspected, cows are possessed of rich interior lives and are prone to conversation when humans aren’t around. While that comic strip may be taking certain creative liberties, it turns out that bovines really do have distinct “voices.” New research shows that cows can produce their own unique moos.

The study, published in the journal Scientific Reports, recruited 18 Holstein-Friesian heifers (virgin cows) at Wolverton Farm in New South Wales, Australia, and had them vocalize into a microphone. The study’s authors wanted to see how their mooing was affected by a variety of circumstances, like when heifers were in heat, when they were about to eat, denied food, parted from the herd but within sight, or parted and out of sight.

The results? Each cow warbled a different moo with an acoustic structure that was distinct from its peers and maintained that sound throughout the different scenarios. These high-frequency noises may someday help farmers sort out a cow’s contentment or displeasure with their surroundings. Previously, few researchers had studied whether cows maintained their vocal characteristics in different social settings.

It will take additional work to figure out precisely what a cow might be displeased with—the animals are relatively stoic and not prone to emotional outbursts—but the research is a step forward to a time when we might be able to identify their feelings and address the cause of their bad moooods.

[h/t Atlas Obscura]