My dog constantly barks at the tv

I have 2 senior spaniel mix dogs and one of them barks at the tv at almost anything: another dog, a dragon on game of thrones, the geico gecko, the mucinex booger. Pretty much anything other than people. We simply cannot watch live tv without the remote in our hands to change the channel during commercials because this little dog has trained to wake himself up when he hears an ad come on. We’ve tried medication, we’ve tried letting him get used to seeing creatures and critters on screen, nothing seems to help. While this isn’t a massive problem, it does get old. Any ideas we could try?