Koala Mating Calls

Scientists doing research on Koalas, have found that they use additional vocal cords to produce low-toned noises during their mating season. These long bellowing calls are continuous while inhaling and exhaling for the male Koalas. The scientists say that no other animal on earth has these extra vocal cords. Specifically, it's the only organ other than the Larynx that creates sound for animals. This organ is found on the outside of the vocal cords, stretching from the larynx, all the way up to the top of the oral and nasl cavities. They are know searching if other animals have this unique organ, or if its solely to the Koala.

http://www.scienceworldreport.com/articles/11321/20131203/koalas-use-additional-vocal-folds-to-produce-low-pitched-mating-calls.htm