Is there someone in your call who can't be heard?
Ask them to play the test sound:
- Click More in the bottom right (triple dots)
- Click Cam/mic settings
- Click the text link Play Test Sound. Do you not hear a test sound? Reboot!
Hate to say it, but if your browser can't play the test sound, it's overloaded. You can first try quitting and reopening Chrome. But to be honest, your browser probably needs a clean start. Reboot might be fastest.