I'm willing to bet 99.99% of the time you hear music from outside a car it's not due to someone being hard of hearing, unless they caused that issue themselves by listening to music too loud.

However, if you are hard of hearing to the point where you are actually disturbing others, I would recommend headphones.

Background noise makes it difficult for the hard of hearing to listen to conversation.

If we cared more for the hard of hearing we would reduce music volumes and make restaurants quieter. Our society doesn't care even though it pretends to.