It seems that the sounds coming from different notification types such as a guardian battle, reinforcements arriving, your attack on a city, an attack by someone, etc. are all very similar to each other, making it hard to identify by the sound what has happened.

I suggest making noticeably different notification sounds for different types of events, so that we can quickly identify what happened (on a high level) without needing to open the battle report for each one, only to see many updates which may not have the same importance to us.