A.D.
Someone said they outgrow it. that isn't necessarily true. My daughter did this high pitched scream when she found her voice and now that she is 2 1/2 it is her way of having a tantrum. We all get frustrated and that is how she voices her frustration...short, but very loud screams. Rather than throwing herself on the floor she screams for a few seconds then stops. We tell her to use her words and inside voice and that always stops it.
It is loud and annoying, but as she is growing older and gaining new words every day, it is decreasing. It reached its height when I was pregnant with her now 5-week old brother. Remember, thy are not mini adults, they are children that are learning what works, what doesn't, when and where to use their loud voices.