Apparently touring alongside the likes of bands such as Killswitch Engage had a major impact on the boys in Underoath, as it's noticeable right from the start of the bands third full length effort Define The Great Line.

"In Regards to Myself" opens the album, and vocalist Spencer Chamberlain makes it a point to showcase a newer more aggressive vocal style sounding ALOT like Howard Jones (Killswitch Engage), yet still maintains his higher register scream.
"A Moment Suspended In Time" is at times reminiscent of Norma Jean, with quirky odd times signatures. But there is more than enough melody injected into the song to ensure that it comes off as signature Underoath.

"You're Ever So Enticing" is classick Underoath, with all the Emo/Screamo stylings that fans of the bands previous efforts, They're Only Chasing Safety and The Changing of Times, have come to expect.
"Salmarnir" (Icelandic for 'Psalm') on the other hand, is an altogether different kind of track. All spoken word, with a total monastery-worthy musical backdrop. Definitely not typical, at least not for this band.

"Casting Such A Thin Shadow" at first seems to be completely instrumental, until it reaches the 3:50 mark, where vocals finally kick in. Ironically, the first few lines come off sounding alot like King Diamond vocally.
"To Whom It May Concern" (which is the longest track on the album, clocking in at just over 7 minutes) closes out the album. All the elements that serve to create the new Underoath sound on this record are represented in this track, from the softer melodies to the more aggressive vocal stylings. They really couldn't have chosen a better closer.