[Seerah]

local f = CreateFrame("Frame")     --create a frame to listen for the event
f:RegisterEvent("CHAT_MSG_SYSTEM")     --register for the event you want to listen for
f:SetScript("OnEvent", function(self, event, msg)     --tell WoW what to do when the event fires
          if strfind(msg, "sold") then     --we only registered for one event, so we don't even have to check to see which one it was
               PlaySound(5274)
          elseif strfind(msg, "expired") then
               PlaySound(5275)
          end
     end)