Desensitized to TV?

Hurley just turned 2, he's a 40lb "mini". He reacts to about anything on TV now. It used to be just dogs. It's progressed to animals, movement, suspenseful music, babies crying, scrolling news ticker at bottom of screen... It seems that "anything" can be a cue to flip out at.

What I'm trying: when TV is on, I watch him and try to interrupt when he's about to react, with command "come, sit, look (at me)", and food reward. This seems to show signs of helping. But inevitably he loses it and is at the TV barking and can't hear me.

I haven't taught "speak/quiet", he doesn't bark very often besides the tv, so I've struggled with how to put it on cue. Saying "quiet" vs "come" won't matter when he's lost it at the tv and can't hear me anyways.

He gets 2.5 - 5 miles walking each day. Lots of attention and play.

Do I need to figure out a more systematic desensitization, like with a vacuum cleaner? Maybe start with having a still frame of something on the screen and rewarding for being quiet? Or will what I'm trying just take time and a lot of treats?

Thanks for any suggestions, resources, and ideas regarding training.

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