i heard demonic sreams in a cemetary

one moonlit winter night, my friend and i were walking through the cemetary that we always used for a shortcut between his house and mine. this time, when we were about halfway through , on the main road that runs through the middle , suddenly out of nowhere, without any warning and "really" loud we were "blasted" from above and all around us, right in our faces, by the most horrible "bursts" of inhuman sounds anyone could possibly hear, ferocious growls, cackling laughter,and wounded animal like shreiks, all mixed together!!! we could afterwards tell that this was one being that changed its sounds from one type to the other in rapid sucession ,we ran so fast out of there and took the two mile long way around instead. of course!?!? no one believed us, how i wish i had a recording, it "would" terrify anyone!!! the sounds lasted about 20 seconds, the lenght of time that we were frozen with fear and couldnt move and they trailed off as we ran away, it didnt follow us out, "why" was this in a cemetary? a place thats always perceived as a final resting place, but my friend and i know that they can be anything but,we were 15yrs old and permanently altered by this bloodcurdlingly weird experience in massachusettes back in 1978,i can still remember what it sounded like every time i think about it.......