I was testing stuff with a deaf character, and realized that when I turn the radio in a vehicle, I see the usual <bzzt> and <fzzt> above that – I think deaf character shouldn't hear the buzzing sounds.
After further testing, It seems that a deaf character can even listen the auditions in car's radio as usual. I checked if I can watch TV or listen regular radio when deaf, but it seems that only vehicles radio is the one that's affected, so it seems like an omission.