Notification settings are relatively complex on a modern iPhone or iPad. The app can play sounds or vibrate the phone without showing any visible notifications. Here’s how to curb a criminal.
Phantom vibrations (and sounds)
It is worth remembering that phantom vibrations are common. Many people have felt their iPhone vibrate in their pocket, only to take it out and realize it didn’t vibrate at all. Phantom sounds may also appear, especially in noisy places. Does your phone’s notification sound actually play? Perhaps it was just another sound in the noise — or the same alert sound coming from someone else’s phone.
But this is not the only problem. Your iPhone might vibrate or play a sound even if there were no notifications in the notification center or lock screen when you checked it.
The app has invisible notifications playing sounds
Apps can have invisible notifications that vibrate your phone or play your notification sound.
To check this, go to Settings > Notifications. If the app is set to «Sounds» without «Banners», it will play a notification sound without showing any visible notifications. If an app is set to «Sounds» without banners but with «Icons», it will display a red notification badge with a counter of new items in the app. It plays a sound when the icon is enlarged, but does not display a visible notification.