Well, in practice, it's not that harmonious. Yes they moan and carry on in mostly-human voices, but if you've ever heard foxes screeching, there's a bit of that mixed in, too. The first time one of those yips squeaks out by accident, they surprise even themselves and get all embarrassed. The fiftieth time...when you're digging around vigorously, on a mission...you care a lot less about what you sound like. But it still freaks out the neighbors.