Organs and Special Tissue
A polar bear's respiratory organs are its mouth, nose, and lungs.
An adult polar bears vocalize most when it's agitated or threatened. Sounds include hissing, growling, champing of teeth, or soft chuffing. Cubs vocalize more often and for diverse reasons. Sounds include hissing, squalling, whimpering, lip smacking, or throaty rumblings. Mothers warn cubs with a chuffing or braying sound.
"Polar Bears." Polar Bears. Seaworld, n.d. Web. 20 Apr. 2013.