One of the new health features baked into watchOS 6 is a Noise app that will tell you when the environment around you is too loud. But just how accurately can a wearable device with a tiny microphone measure noise?

You’ll be surprised. A comparison with an actual decibel meter proves Apple Watch does an unbelievably good job.

The Noise app is designed to help Watch wearers maintain healthy hearing. It recognizes ambient sound levels and alerts you when the environment around you is too noisy, and allows you to measure noise in real time.

You’ll get a notification on your wrist when noise levels reach 90 decibels, at which point your hearing can start to deteriorate — especially if you’re exposed to this volume for four hours or more per week.

But should you take any notice of the Noise app? Absolutely!

Apple Watch is a great decibel meter

Software development manager Blake Helms put the Noise app’s accuracy to the test against a real decibel meter. As you’ll see in the short video below, Apple Watch does an impressive job at matching its performance.

When you consider that the decibel meter used in this comparison is equipped with a specialized microphone designed specifically for this purpose, it makes Apple Watch’s ability to keep up even more surprising.

For anyone curious about the accuracy of the #WatchOS6 Noise app, here’s a comparison with a decibel meter this morning. cc @stroughtonsmith @marcoarment pic.twitter.com/aXrK6iF1D7 — Blake Helms (@helmsb) June 16, 2019

You’ll notice Apple Watch doesn’t sample as frequently as the decibel meter, so the latter updates its reading more often. But the Watch is able to provide a near-identical reading on a consistent basis.

The Noise app is all you need (probably)

“I was shocked at how accurate it is,” tweeted Helms.

“I honestly was expecting a lot less considering how small the [Apple Watch] microphone is. I did a few more tests with constant volume tones and it’s pretty consistent within 3-5db.”

Helms notes that the Watch caps out at 120 decibels, but that’s fine if you don’t find yourself in extremely loud environments on a regular basis. The Watch is more than good enough the rest of the time.

“I normally check a few places with my meter,” Helms added. “I may start using the Watch.”

watchOS 6 arrives this fall

You’ll be able to try out the Noise app for yourself when watchOS 6 rolls out to everyone this fall — but only if you have Apple Watch Series 4. The update itself will be compatible with Apple Watch Series 1 and later.