Music4Games informs us of their Interview with Blizzard Audio Director and WOW: The Burning Crusade Lead Composer Russell Brower:
M4G: What was the total amount of music you ultimately delivered for The Burning Crusade?
Did the infrastructure for the expansion pack offer any new music opportunities as a tool or music availability that did not previously exist with previous WOW releases?
Russell Brower: The expansion set came in at about six hours of new music. This represents a significant increase over the original 2004 release, which contained about two hours of music to go with a larger amount of visual content. We also added about two hours of music in the content patches that were deployed between the game’s initial release and January 2007. We just completed another hour for the next content patch as well.