His thing was to lean over his plate and shovel food into his mouth at a rapid fire pace, usually pretty noisily. Barely chewing as he went.
Honestly, nothing helped. Getting on his case didn’t change anything for more than a minute. 5 polite bites later he went back to shoveling food into his face without realizing he was doing it. He also had adenoid issues that made him a bit of a mouth-breather which added to the noise. It caused lots of conflict and hurt his feelings when he was a little guy. I unfortunately got frustrated and overbearing as his dad.
Eventually he got his adenoids out and just kind of grew out of the bad table manners on his own as a teenager. But I still sometimes feel like a jerk for always being on his case.
I am not saying you shouldn’t try to correct it for your son. Just saying don’t be a mean dad like I was.