If you came across California mice in the wild, you wouldn’t hear a thing. Their jabber is ultrasonic—humans hear it only when it's slowed to five percent its original speed. But that’s when the imperceptible squeaks morph into a vocal range that’d put Mariah Carey to shame.

Mice, you see, regularly vocalize to communicate in many different situations—which researchers did not know until recently.

“It’s an under-appreciated part of biology of one of most diverse groups of mammals,” says Matina Kalcounis-Rueppell, a professor of biology at University of North Carolina, Greensboro who discovered about a decade ago that these mice vocalize.

These sounds range from coos to startling barks. New research published in Frontiers in Ecology and Evolution shows that when these