text: According to Animal Diversity Web, orangutans have a vocal repertoire of about 13 sounds, including lip smacking, screaming, roaring, and grinding their teeth. Males also emit loud groans, which can be heard by a human up to 1 kilometer away. \nThere's a sound clip of these groans here\nhttp://www.rollinghillswildlife.com/sounds/orang_longcall.mp3