Dad maintains constant chatter, often same phrases over and over, except when sleeping or eating. How to manage?

My 89 yr old dad with vascular dementia has been living with me for the past 2 years. I work full time and have in home caregivers M-F, and some hours on Sat and Sun. In the past 6 months or so he has started talking non-stop... often talking to or arguing with the characters on TV. Sometimes its a repeating phrase, Oh Me, Oh My, Oh my god. When asked what's wrong he says nothing, it's just all he knows how to say. We've tried offering NEW phrases but he goes back to the old ones. The caregivers seem to be able to tune it out, but I just can't for some reason. I get out for a few hours but as soon as I'm back, that's all I hear. It's starting to drive me crazy! Anyone else found strategies for dealing with this? It's the first thing he says in the morning and the last thing he says at night.