One of my favorite dive operators will not allow music or anything but a Marine Required radio on the dive boat. He says when divers are in the water he wants the boat crew with no distractions, alert and watching for divers in trouble. I feel a heap safer diving from his boat because of it. I was impressed on a dive I sat out, he knew where all his divers were and even knew which divers in some cases. He knew from the bubbles about current and had a mermaid line ready to throw when he saw a couple divers were ascending and were going to get caught in cross currents!