Now this is a scientific breakthrough! A study done in Hugary found that people really know what their dog's growls and barks mean. The scientists had people listen to audio recordings of their dogs barking while eating, playing, and facing a threatening stranger, and 63% of the time people could identify the dogs noise. 

As an added bonus discovery, they found that women with experience with dogs were right more often than men. I think we are just better listeners :)