Hmm… Some of the readers faced robotic voice issue on their Android HTC HD2. You will have robotic voice issue if you did not execute CLRCAD.exe. Besides that, they are 2 factors that will cause it too.
How to fix robotic voice in Android HTC HD2?
I am using both combination above since day 1. And do not have any robotic voice issue at all. You might want to try it too.