Users of Google Pixel Buds have been reporting issues with the sound volume during phone calls. Here are some methods that have worked for others in fixing the volume issue.
Disconnect and Reconnect Bluetooth
Volume issues are common with any Bluetooth device, not only the Pixel Buds. Simply turning Bluetooth off then on again usually clears things up.
- Swipe down the notification panel from the top of the screen using two fingers.
- Tap the Bluetooth icon to turn Bluetooth off.
- Wait about 5 seconds, then tap the Bluetooth icon again to turn it back on.
Restart Phone
- Place the Pixel Buds in the charging case.
- Swipe down the notification panel from the top of the screen using two fingers.
- Tap the Bluetooth icon to turn Bluetooth off.
- Press and hold the “Power” button on the phone, then select “Restart”.
- Once the device is restarted, try using the Pixel Buds again.
Update Buds Firmware
Ensure you have the latest firmware for your buds. You can check the version by opening the Google app, then selecting “Menu” 
> “Settings” > “Google Assistant settings” > “Pixel Buds“. Firmware version 1.1767.6040-G1-61495-545 was the most current at the time of this writing.
The firmware is updated automatically. You can try to force an update by using the buds for about 10 minutes, then placing them back in the case.
Hard Reset
Reset the Google Pixel Buds back to the factory default setting so that you may set them up with your device again.
- Place the Pixel Buds in the case.
- Hold down the button on the case for about 15 seconds or until white light starts blinking. It should pop up a notification saying you have new pixel buds to set up.
- Walk through the steps to set your buds up with your device again.
dan says
None of these worked for me. My problem was basic stupidity, but it’s worth posting here because I can see it happening to someone else. The shape of the earbud makes it easy to put in your ear backwards — i.e. with the thicker part to the inside of your ear and the thinner part (with the speaker) facing out. The smaller part goes in and you get to look like Shrek … but the sound volume is just fine.
//dan.