#1: Turn on Visual Alerts
This will make your phone flash whenever you get a notification.
To do this:
Go to Settings and select Accessibility
Select Audio/Visual
Toggle on “LED Flash for Alerts”
#2: Turn on Sound Recognition
When you activate this, your iPhone will listen continuously for certain sounds – such as a knock at the door, water running, or a dog barking – and notify you when it hears it.
To do this:
Go to Settings > Accessibility and then select Sound Recognition.
Toggle Sound Recognition to on.
Tap Sounds, and then choose the sounds that you want your iPhone to recognize.
You’ll see a handful of preset sound options, like a Dog Bark, Door Knock, Water Running, and more.
Select the sound you’d like your phone to recognize and toggle it to on. We’d also recommend setting a different custom alert tone for each sound you choose.
From there, test it out. You will hear a sound and notification when the sound you’ve chosen has been detected.
Note that Apple indicates that this feature is not 100% accurate, and shouldn’t be relied upon in emergency situations.