Generally we see Tim Burton pair up with the just as dark movie scorer Danny Elfman, but in the film adaption of Sweeny Todd, Tim Burton couples his dark and twisted visuals to the witty and classy songs of composer Stephen Sondheim to create a heightened feeling and extension of the protagonist, Sweeny Todd's, newly found crazed mindset.
Here are a few examples of the implementation of various songs within the film to reflect the crazed mindset of Sweeny.
"The Worst Pies In London"
This song practically sets up the premises of this film. Mrs. Lovett outright tells Sweeny that her pies are the worst in London, but alas, he should still eat them. This gears the audience towards a mindset of: weird/off things are the norm in this world. Therefore, this is a clear parallel to how although Sweeny was once a normal man and thus is able to determine that killing people is wrong, he still goes ahead with it later on in the film.
This song is first performed when Sweeny first gets to give Judge Turpin a shave. We know that Sweeny intends to kill this man, and yet we hear them singing an almost peaceful and thoughtful sort of song (which further accentuates the insanity of Sweeny.) Sweeny does not kill the Judge until the second time he gets a chance to give him a shave. With the visuals of Sweeny slitting the Judge's throat paired with this music, it is quite obvious that Sweeny has lost touch with his old normal self.
This song is quite climatic for it is the only composition that truly embodies the insanity of Sweeny. The other more peaceful songs clash with the gory visuals, thus making us feel a sense of skewed perspective. This song just throws his mindset right in our faces as we hear Sweeny preach on about how everyone deserves to die and we see him killing off many people.
All in all, Tim Burton does a beautiful job pairing off his dark visuals to the brilliant compositions of Stephen Sondheim.