Adult polar bears vocalize most when they're agitated or threatened. Sounds include hissing, growling, champing of teeth, and chuffing.
Cubs vocalize more often and for diverse reasons. Sounds include hissing, squalling, whimpering, lip smacking, and throaty rumblings.
Mothers warn cubs with a chuffing or braying sound.
Polar bears also communicate through sight, touch, and smell.
A male polar bear initiates play fighting by approaching another male with its head down, mouth closed, and eyes averted. The bears usually make contact by gently touching or "mouthing" each other around the face and neck. They then proceed to rear up on their hind legs and try to push each other over with their forepaws.
A mother polar bear can comfort, protect, or punish her cubs by using her body, muzzle, or paws.