Is the listener considered sinful when involuntarily hearing music in public transportation, and are angels bothered by such music if earphones are used to avoid hearing it?

If you condemned forbidden music and they did not comply, then there is no sin upon you.

Riding a bus that plays music: - If you are able to go to the university by another means, then you must not ride the bus, so as to depart from a place of sin when able to do so. - If it is difficult for you to go by another means, then there is no harm in riding it, and it is better to put something in your ears to prevent hearing. - You are not obligated to block your ears from hearing, and there is no sin upon you for merely hearing unintentionally, as hearing differs from intentional listening.