I don't know about your kids but my kids do NOT understand volume control in the slightest.
It doesn't matter if someone is sitting one foot away from them my students will YELL their conversations at each other.
I cannot stand a LOUD classroom. I don't mind controlled chaos but I absolutely abhor just straight up chaos.
I have seen the "ball noise tracker" that is going around Pinterest, but there are two issues I have with that.
1. It is blocked at my school
2. I Know the kids would find it too much fun to make the balls bounce (and then scream and laugh about the fact that they are making the "balls" bounce)
I did a search and found this useful online tool: