This issue was annoying me for a while and none of the fixes proposed online were able to fix the problem (including completely Chrome reinstall). This is how I’ve eventually resolved the problem of some of the YouTube videos playing without a sound in Google Chrome.
This fix is for Windows 10, but the approach should be platform agnostic, as long as you know where to find your sound card settings.
In Windows 10, right click on the speaker icon:
Then select Playback Devices:
The sound setting window will open. Right click on ‘Speakers’ and select: ‘Configure Speakers’
In all likelihood you’ll see that your speakers are set to either ‘Quadraphonic’, ‘5.1 Surround’ or ‘7.1 Surround’.
If you do not have such a speaker configuration, it’s the reason for sound not working in YouTube, because some of the YouTube videos are sending sound to speakers which you do not have configured.
So in order to fix the problem, simply change the setting to ‘Stereo’ and keep pressing ‘Next’ button until it’s applied.
Once done, restart Chrome and you should be good to go.
Here is a video of how to apply the setting, if that makes it easier:
Let me know if this helped.