Need Help Detecting Who Made a Critical Hit

[Macer]

Ok, a mod I use (CombatSounds) detects critical hits and plays special sounds.

My problem is it detects anyone's critical hits on my target. I want to modift the lua to only play the sound on my critical hits.

Here is the current code:

function CombatSound_OnEvent() 
   if( event == "UNIT_COMBAT") then 
      if (CombatSoundConfig.useCrit) then 
	if (arg1=="target") and arg3=="CRITICAL") then 
	PlaySoundFile "Interface\\AddOns\\CombatSound\\Sounds\\crit.mp3"); 
	end 
      end 
   end 
end

Can I add UnitIsPlayer() somehow in there? If so, how? I checked thottbot and they only list 2 arguments for UNIT_COMBAT, yet this code references arg1 and arg3