For example the normal English language setting will, every so often, pop up a box and a nice polite female voice will say; "Virus database has been updated".
When you have Pirate Talk enabled a rough and ready male voice will say; "Yar blacklist of dangerous sea dogs is safely aboard".
Check the shots and how to do it here....
The shots are from the old version of Avast but they still apply to the latest version.
http://techstrike.co.uk/how-tos/383/