I've had my phone for over two years and this voice began only a couple of days ago. It is very annoying; previously I heard only a subtle "ding" when an email came in, vastly preferable.
In your email apps (check them all, because some other one may be getting notifications of emails), check the selected notification tone. If that voice is one of them, change it to the ding sound (or freeze or uninstall one or more email apps - you should need only one).