Pixel Buds has automatic ear detection for when they're in your ear or when you take them out. If your Pixel Buds detect that you've taken them out, your current audio selection will automatically pause. When you put them back in, the audio will automatically resume. While paused, you can also tap once on the earbud to resume listening.
In-ear detection is enabled automatically if you pair your Pixel Buds with an Android 6.0+ device with Fast Pair enabled, and will then remain on for any connected host device. You can disable this feature manually using the Pixel Buds app. For Pixel Buds that have in-ear detection turned off, triple tap the right earbud to manually sleep and wake your earbuds.
Turn in-ear detection on or off
Pixel Buds A-Series and Pixel Buds (aka Pixel Buds 2nd Gen)
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Depending on your device, you can change the settings for your earbuds in different ways:
On a Pixel phone with Android 10+: Go to Settings
Connected Devices
by your paired Pixel Buds name.
On other Android devices: Open the Google Pixel Buds app.
- Scroll down and tap In-ear detection to turn it on or off.
Connected Devices 
by your paired Pixel Buds name.
.Pixel Buds Pro
Depending on your device, you can change the settings for your earbuds in different ways:
On a Pixel phone with Android 10+: Go to Settings
On other Android devices: Open the Google Pixel Buds app- Scroll down and tap More settings.
- Tap In-ear detection to turn it on or off.