You would appreciate that there is no dearth of such examples where some employees always behave in a nasty, irritating manner and continue to disrupt the general discipline of the office environment. Since you are new to your organization, you might have been feeling a little odd to speak with this fellow directly. I am sure the type of behavior this peon displays in the office would not have been liked by others also, but they are keeping quiet because they are waiting for someone else to initiate. Human tendency is such that we always tolerate nuisance, ill behavior, turn a blind eye, and wait for someone else to bell the cat.
With my experience, I can advise you on this. Please call this guy into your office and do a small counseling session. Tell him that since he is the most senior employee of the organization, all new employees should look up to him for good behavior, direction, and support. He should lead by example and try to set a positive tone so that the new employees learn values, good behavior, and a good attitude from nobody else other than the most senior employee of the organization. Counseling has magical power, and if done properly, it will definitely bring a sea change in his behavior.
You can also mention that we all appreciate his good taste in music, but listening to songs at a high volume not only disturbs all of us, as we mostly work on tasks that require good mental focus, but also disrupts the general discipline and decorum of the office, which is not right. As a good counselor, you may suggest to him to use earphones if he really loves music so much (although it is not keenly advised).
I think this small counseling session will work wonders to your advantage. After all this, if it doesn't work out, then please don't wait any further. Discuss the same with your fellow colleagues, take one of them with you, and explain the situation to your senior. I believe this problem will be sorted out for sure.
Regards,
Rakesh Pd Srivastav