The Panopticon/the twelfth Doctors accent.

From Tardis Wiki, the free Doctor Who reference

I think I have a theory about why the twelfth doctor has a Scottish accent the last thing the eleventh doctor was thinking before he regenerated was Amy. Maybe the Tardis changed the way the doctor's voice sounded by its translation circuits so to ease and reassure the doctor into a new generation cycle I'd like to Add this theory to the wiki .