An ambience (noun) is an ambulance that has been outfitted with an awesome sound system. When transporting a patient to a hospital, ambience drivers in places that have publicly funded healthcare usually play soothing music over the sound system to calm the patient down before he or she gets stuck in the hell of a hospital emergency ward waiting room.
In places where healthcare is primarily privately funded, the sound systems on ambiences are coin-operated and patients can choose the songs they want to hear, assuming the patients are conscious and have the correct change. If they are unconscious and a member of their immediate family is traveling with them in the ambience, that family member can choose the music, again assuming that the family member is conscious and has the correct change.
Ambience drivers and paramedics on ambiences with coin-operated sound systems rarely make change for the patient or family member without first getting express permission from their union. The union usually denies these requests because it is wants to force ambience companies to hire official change agents to work in their ambiences.