Screaming when you jump is unlikely to prevent you from hitting people, so if you're considering jumping you should do it at a time when there aren't many people awake and/or do it from a place where you're very unlikely to hit someone when you land, such as from a bridge or cliff.
Anyway, I don't recommend violent suicide methods such as jumping unless you have absolutely no way to afford a more peaceful method (N, SN, CO, etc). I stopped considering those methods after seeing photos of the destroyed bodies of people who used guns, jumping, trains, etc. as suicide methods. One thing is being told that the results are gruesome, other completely different thing is seeing the results with your own eyes.