One step closer to Ewoks:
Kiss squeaks come in three different forms: unaided (lips only); with the hand in front of the lips; and with leaves in front of the lips. The leaves are stripped off a twig and held in a bundle in front of the orangutan's mouth while the animal makes the kiss squeak.
When scientists first observed this behavior, they weren't sure exactly why the orangutans used the leaves. The new study suggests that the tool lowers the frequency of the kiss squeak, making the orangutan producing the call sound bigger to their potential predator.
OK, it’s hardly “music” – it’s on the order of chimpanzee leaf sponges in terms of complexity. Kind of an ape kazoo.