Nope, I can't scream.. I can whistle like a fiend, I have to really drop my voice to a growl if I am telling the animals "NO", but I can't for the life of me scream...
My mother can't either.. We are naturally very soft spoken and the west country burr doesn't help.
If I want to get someone's attention quickly I have to whistle, which always strikes me as VERY rude, but I don't have a choice really..