Additional vocals Alter Bridge song "Words Darker Than Their Wings"?

The song Words Darker Than Their Wings, the 14th track on Alter Bridge's third studio album AB III, features another voice in addition to Myles Kennedy, the lead singer of the band. The album insert lists Mark Tremonti as guitar and backing vocals, so I ume he is the additional singer. However, the voice reminds me of Josey Scott, the lead singer of Saliva. Does anyone have a definitive answer on this one?