Barred owls are slightly smaller, slightly less fierce, and their appearance is not nearly as formidable. Frequently, barred owls are more vocal than the horned owls, even calling occasionally during daylight hours. For my money, the most startling of our owl calls is that of the screech owl, an efficient little mouser barely bigger than a robin. But there really isn't an adequate way to put words to the call. It combines whistles and whimpers with the whinny, along with several quavering sounds.
Some people consider the call akin to demonic laughter, others think of it as forlorn.
I don't hear it as sad, just wild. The last time I heard a screech owl, I was walking a country road and admiring the stars. When the owl suddenly cried out from a brushy fencerow, it took a moment for me to recognize the sound, then several more moments for the shivers to subside. The fields and forest quickly fell silent again, but the evening had changed. Owls can make any night feel wild.