Elephants have a far bigger vocal range than Julie Andrews: ten octaves! They have at least 10 basic call types which can produce a huge variation when combined. Like the situation with whales, humans have done a lot of research and have tapes of elephant sounds, but have not cracked the code as to what exactly they are saying to one another. What we do know, however, is that elephants talk like we do, with both verbal and nonverbal communication.
Elephants also use infrasound, sounds so low they do not get registered by the human ear. If you ever wondered why animals seem to be able to predict natural disasters, it is likely because they pick up on these low sounds rumbling from nature, warning them of volcanoes, avalanches, and earthquakes.
(Photo taken at Elephant Nature Park)