That is a question many film-goers want to know. What's up with the voice?
The voice of Christian Bale's Batman is raspy and almost like a whispery growl. When I heard it first in the last Batman movie I nearly laughed out loud. This time I knew what to expect, but it still sounds rather silly to me.
Here is an interesting article to read about the voice of Batman: Bale's Batman voice too much?
All-in-all, this Batman flick, "The Dark Knight" was excellent, great acting especially by the late Heath Ledger who played Batman's nemesis, The Joker. This Batman was darker than all the rest, and there was an actual plot that could be followed. Despite the voice, Christian Bale's portrayal of Batman is the best to date.
UPDATE: After an anonymous commenter pointed this out, I did some research and found out that Batman's voice is produced by a voice modulator in the cowl of his Batsuit.
How the Batsuit works.
"The microphones in the ears are combined with special earpieces in the cowl that give Batman superior hearing in the field. The microphones can also be used to amplify Batman's voice and broadcast it through a discreet speaker in the suit. This is what gives Batman's voice that distinctive, disembodied and unearthly sound."
But it still sounds funny. Overly evil.