Originally Posted by
eirman I'm quite sure that you always get an audible notification for every inbound message when exchanging a sequence of messages with somebody, regardless of the open/closed status of the application.
That might be the case for the Samsung Messages app (I don't have direct experience with it), but I know for sure that Google Messages (and a number of other stock messaging apps) won't give you audible notifications if the app is open. This has been discussed a number of times on the forums previously, and the usual solution is to try a 3rd party SMS app like Textra.