I'm going to talk while a jazz band is playing a quieter song at a cafe
Okay, but why do that specifically when there's a quiet song playing?
I don't care about the feelings of other people, they wouldn't care for me
It's expected that show respect for the band. It 's considered rude to ignore social norms while at a restaurant.
I don't care. I just want to talk to my friend and don't want to listen to that rubbish.
Doing so will be disruptive to other people in the restaurant and can get you removed from there or worse, ban you on that restaurant. I won't recommend you talk while the band is playing or at least do it very quietly where no one is disrupted.