iphone sounds - no clue what they are for

Whatever is alerting you has non-persistent notifications turned on. You wait a minute after the ding, go look at your phone, and don't see anything, I'm assuming.

Swipe from the top left down (after you unlock), and it'll show the most recent notifications.

If you want to make the content stick around, go to General, Settings, Notifications. Change the "Display as" to stack or list (assuming you're on the latest iOS). Make sure "Show Previews" is set to Always.

After that, each app can get a category of how to notify you (banners, sounds, badges) and each app can be set to disappear quickly, or not at all. But the first para will probably let you know what you need.