Apple will update the Apple Watch with its latest software, watchOS 6 in the fall. It'll include a new feature called Noise that can be used to notify you if the environment you're in is loud enough to damage your hearing. I tried it out using the watchOS 6 beta, and it's pretty neat.
Noise is off by default. But you can turn it on inside the new watchOS 6 Apple Watch app on your iPhone.
I was able to set up notifications for when my Apple Watch detected a specific noise threshold. Apple recommended sound levels from the World Health Organization, which let you get notifications for when you hit certain decibel volumes. Per the recommendations, you shouldn't exceed:
I set the controls right in the middle, at 90 decibels, but you can choose to get a notification when your watch notices the volume in your environment is more than any of those thresholds for longer than three minutes. Then, on my Apple Watch, I turned on one of the watch widgets (Apple calls these complications) to show me decibel readings in real time.
The watch showed the environment I was in was at a safe 34 decibels just sitting at the computer. It jumped to about 45 decibels when I was typing, but again that was still safe. I turned on Spotify and it jumped up a little bit more:
Then I cranked up the music volume and my dog started barking. According to the World Health Organization stats, I shouldn't be in this environment for more than five hours a day.
Finally, I was able to get it up to 100 decibels by whistling as loud as I could right into the Apple Watch:
Had I stayed in this environment for longer than three minutes, I would have received a notifications that the sound level could be high enough to damage my hearing. The widget is useful and is a good way for you to see how dangerous some of those environments can be. In many cases, I probably would know if something is too loud, like at a concert, where some people wear earplugs for extra safety.
Apple says that water or wind can affect the accuracy of the ratings, so it might be off if you're out on the beach or just took a swim. Also, Apple says it "does not record or save any sounds to measure these levels," so it's not listening to what's going on around you.