darth_ender said:
I've not seen it, so I cannot comment on the film itself. However, my dad is a great singer (not lying when I tell you he was once a part of the Mormon Tabernacle Choir back in the '60s). His speaking voice is certainly deeper than mine, but he can sing higher and more powerfully than I can (and while not of his caliber, I'm a pretty good and somewhat trained singer). So it is reasonable.
I learned a lot about singing by hearing various interviews with fantasy author Tracy Hickman, about his audition process trying to make it in the Tabernacle Choir.
On a side note, I wish someday a horrible fight breaks out there, just so the news headlines would read "Slobberknocker in the Tabernacle!"