The National Fire Protection Association (NFPA) recommends testing your smoke alarm monthly, but data shows that 90% of Americans don’t do this as often as they should. So, the 2nd gen Google Nest Protect has a microphone. It can listen to its horn and speaker tests and confirm that they’re working. This helps make sure Nest Protect will speak and sound an alarm when there’s smoke or carbon monoxide.
During Sound Check and Safety Checkup, Nest Protect's microphone is on for a few seconds to make sure the speaker and horn are working. During that time, the microphone is checking to hear Nest Protect make this sound:
Sound Check
Google Nest Protects can automatically test their speaker and horn once a month, at the time of day you choose with Sound Check. If your Nest Protect has a working Wi-Fi connection, you'll receive an alert on your phone letting you know when it's about to happen. Learn more about Sound Check.
Safety Checkup
Safety Checkup is a manual test to check if your Google Nest Protect’s sensors, power, Wi-Fi connection, speaker, horn, and light ring are working. You can run a Safety Checkup for a 2nd generation Nest Protect with the Nest app, with the Google Home app, or press the Nest button on any Nest Protect.
Nest app
If you have at least one 2nd gen Nest Protect in your home, you
can run a Safety Checkup with the Nest app.
1. Sign in to your account in the app.
2. Select Nest Protect on the home screen.
3. Tap Checkup at the bottom of the screen.Home app
- Open the app and tap Favorites
or Devices
.
- Tap your Smoke & CO alarm’s tile and select the device name.
- Tap Run Safety Check
Start
or Devices 
.
Start Nest Protect
1. Press the Nest button on a Protect. The blue light should turn on and it will speak to you.
2. When it says "Press to test", press the button a second time.
The microphone will only turn on at the end of Safety Checkup, when Nest Protect is checking its
speaker and horn. Learn more about Safety Checkup.
Turn off Sound Check
You can turn off Sound Check during the setup process or by going into Settings in the
Nest app 
Home app
- Open the Home app
and go to Favorites
- Tap the Smoke & CO tile.
- Tap Settings
- Switch off Allow monthly sound check.
Nest app
- Open the app and select your Nest Protect.
- Tap Settings
- Switch off Allow monthly Sound Check.
You can also choose to skip a test any month. Once you've enabled notifications, Nest
Protect can send you a message about five minutes before it runs a test, where you can
choose to skip this month's test. Nest Protect will try again next month.
If you disable Sound Check, but you still want to test the speaker and horn, just run a Safety
Checkup. The microphone in Nest Protect will listen for the speaker and horn every time you
run a Safety Checkup, even if Sound Check is disabled.
We know that your home is a private space, and we've designed Sound Check and Safety
Checkup with that in mind. You can read more about our commitment to user privacy here.