I am finding that I receive audible notifications for emails, though after receiving many, they just seem to stop, even though new messages are coming in.
Yes, I have experienced this....it happens every so often, and sometimes even the visual notifications will stop, and I have to turn the Sync off and then turn it back on
The Sync, like to turn on your gmail account....you can do it in Settings in Accounts & Sync.....and also on the Power Control widget, its the button right next to the brightness button