ChainsawAsh said:

In the commentary, the director says that the voice sounds like that because he wasn't allowed access to any old Dalek voice recordings, and he didn't have any old Dalek episodes with him to watch for comparison, so he did the voice himself from memory. Poor memory, it would seem.

I'm not going to be changing anything about the film itself for this disc. However, now that I've got the whole movie running at the proper speed, a fan edit might be on its way after the standard release...

--edit--

Oh, and which one of you is ugnaught over at /r/doctorwho?

According to this, the Dalek voices were originally all right but they were later changed for fear that they could not be heard. Ah well. I actually do seem to recall something about the director doing them himself.

Oh and a possible fan edit! How exciting! :-) A little bit of cutting and this movie could probably be a lot more fun and more like the show.

By the way, I'm not ugnaught.