I said a sentence into the mic and made its tempo and pitch very slow and low. You could probably use the part of it that sounds like a screech(which was literally me pronouncing "ssuck")for some kind of video game monster like scp 096 (hence the scp tag).
It's a scream recorded for a project, most convincing part of that project, thusly been using this scream in other projects as my very own wilhelm scream.
This is an alien scream effect i made by taking my scream i recorded earlier and reversing it adding a "wha wha" effect in audacity and then i copied that, placed it after the first, and reversed it again.