I can make a really loud noise that sounds like a Nazgul from Lord of the Rings.

To do it you have to pull air into your lungs against the resistance of your vocal chords. With low power it sounds like an old man/woman dying but with high power it sounds like a hawk. It takes some training because if you try to force it will aggravate your vocal chords but with some practice you can make a yelling-volume noise that does not at all seem human.

Bonus Story: I was on the brewery tour for Yuengling in Pottsville, PA, USA. It's one of the oldest American breweries because it survived prohibition by using a small cave to shuttle beer out of the brewery. As part of the tour they take you through the unlit cave and the tour guide just going through the motions with the energy of Ben Stein doing preventative maintenance. In an effort to liven up the tour, when we got to the darkest parts I yelled, "Oh fuck, bats!!" and did the Nazgul shriek. The whole group ran out of the cave.

The tour guide was very annoyed and assured everyone there were no bats and bats don't sound like that anyway.