Loud noises are annoying but also potentially damaging to your hearing. Introduced in watchOS 6, Apple’s Noise app can alert you if surrounding sounds are above a safe level that could lead to hearing problems. By setting a certain decibel threshold, you can receive a notification from the app if the ambient sounds are too high.
To set this up directly on your watch, go to Settings > Noise, then tap Environmental Sound Measurements and turn on the switch for Measure Sounds. Go back to the previous screen and tap the option for Noise Notifications. Here, you can set the decibel level. If your watch determines that the surrounding sound is too loud, a notification pops up to warn you.