There's no negative modifier on sonic scream, should be easily resistable.
Sonic scream.
http://lucy.allakhazam.com/spellraw....15&source=Live
This is for the elemental earth strike, which is what lvl 50+ earth pet uses here. You can see a few changes over the years as far as pvp resists goes. Not sure what resists calc they use here.
http://lucy.allakhazam.com/spellraw....22&source=Live