Screaming technique, help me out!

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Okey so i've been trying to learn how to scream properly for a long time now and i can do something that kind of sounds right, but i really don't know what i'm doing or if i'm doing it right. All i know is I start with a low frying noise and then I just push more air to make it higher/louder.

I've posted a link to a short clip below where i'm trying to scream. Can anyone tell me what kind of technique i'm using or if i'm using any kind of technique at all? I should also mention that after about 5 minutes of doing this I can't do it anymore. It doesn't hurt, I just can't do it after a while.

http://vocaroo.com/i/s13QWJiSmd0z

any advice on what i can do to improve my screaming is greatly appreciated! thanks!