April 08, 2013, 3:03 PM — Here's how you can change the dialect in Speak Selection on your iPad, iPhone or iPod.
1. Go to Settings.
2. Go to General.
3. Tap on Accessibility.
3. Tap on Speak Selection.
4. Tap on Dialects.
5. Tap on your preferred dialect from the list of options:
For more, see the original article at the link below.