He might get to be stone deaf in his dotage much earlier than normal because of his noisy in-car environment, Joan. I know couple of people who played in big name bands who are now hard of hearing (in their fifties) because they spent a number of hours per week practising and playing in front of huge Marshall speakers.
One of the great lessons I learned was when I went to see Doctor Feelgood in Glasgow. They had NO huge banks of speakers a la Led Zep or Deep Purple, just a couple of small (maybe 70W) combos about the size of suitcases, set on chairs. These were miked up to the house PA system, and the sound was perfect. You didn't come away with your ears buzzing.
I'm with Spike Milligan in believing that noise, not drugs, is the curse of modern life.