Sound when time gets critical doesn't work?

So I have this setting, "Sound when time gets critical" turned on under Settings->Chess clock but I don't hear any sound at all.
I'm using the standard sounds.

Is it just me? Am I too focused on the game and miss it?

Can you hear sounds of moves?

yes. Move sounds, that beep when games starts/ends.

I don't really know... I can hear the sound. But sometimes the red indicator of time doesn't work.
Try "Robot"...

Maybe it's just me. I get so focused on the game I don't hear it.
When does the time alert happen?

It usually happens 15 seconds before your game time ends.