I don’t understand the meaning of shout over as it has been used in the following passage from Patricia Highsmith’s novel, The Talented Mr. Ripley:
A well-dressed Italian greeted Dickie warmly and sat down at the table with them. Tom listened to their conversation in Italian, understanding a word here and there.
“Want to go to Rome?” Dickie asked him suddenly.
“Sure,” Tom said. “Now?”
The Italian had a long, gray car with a loud radio that he and Dickie seemed happy to shout over. They reached Rome in about two hours and the Italian dropped them in the middle of a street and said a quick goodbye.
Could someone please explain to me what to shout over means as it’s being used here?