Can you have ear plugs in your ears when playing a tournament round?

I want to have also the answer of this question. I played a golf with 3 singles yesterday morning. One person played a golf all the time with have ear plug and listen a music. Problem is that he went teebox after hitting his driver shot, even though other player is ready to hit driver shot. So, I told him "Excuse me, I am going to hit driver!!" His answer is "WHAT!!!", because the person who has listen a music can not hear me. This problem happened continuously on the fairway, green as well as teebox. I understand golf is mental game, so it is very important keeping control mind. I think he is not a slow player, and he may be low handcapper (He played very well). However, these problems were totally screwed me up. I want to know what I should do at this situation. Thanks,

Tony Jacklin played the 1981 Open Championship with wax earplugs in....

I usually play with music, but I put it on a very low volume so I can hear other things too, like.... FOUR!!!!!

Also, not to be rude, I won't put the plugs in till I'm ready to hit and only put one ear in, just in case.

I find that music really helps me to relax and take my mind off of bad shots rather quickly... and to tell you, I need that a lot!