You could reward the behaviour you DO want but this is way past that.
Just start on a disciplinary process. I know in the US that there is a very different process to the UK but the root (etymology) of the word "disciplinary" is about learning (discipulus is Latin for "learner") and the intent of disciplinary is not to dismiss someone but to change their behaviour.
If this was the UK we would approach this first with a "file note" which is not formal disciplinary but is a note to say "I've had a conversation with the person about their behaviour and the need to change." This helps you if you need to go further.
Secondly, if the behaviour doesn't improve, you'd do a disciplinary investigation (or rather an independent manager would). They'd sit that person down, ask them to explain what happened, get witness statements if necessary which it probably would be in this case, you'd need to get evidence of when this person has broken the rules. That manager then recommends if disciplinary is advised. Probably yes. You'd then sit down with the employee who would have the right to be accompanied, present the evidence, then decide if a sanction is warranted and at what level if it is. Probably for this it would be at the first level which would be "verbal warning". Despite the words, you'd still then put it in writing, how long it's valid for, what for etc and put on file.
If within that timescale, they contravene the rule again, you'd rinse and repeat working your way up to written warning, final written warning then dismissal.
Yes it's onerous and part of our history of strong union involvement in the workplace but actually in this case, I don't think you'd get further than written warning before the behaviour changed or the person decided to leave.
Could you take some of that approach? I know you're not obliged to in the US but even if it's just to sit down with the person and understand "look, why is it you are not following this rule, I want to understand?" It might be something that they really feel stressed, bored, etc and want music to pass the day. If they're a great employee in other ways, it might be that there are compromises to be had. Music in the workplace, a change of role to one they find more challenging etc.
Not all employees see the British system as fair nor as genuinely a way to solve a problem rather than get rid of someone but I've had multiple employees who have been on disciplinaries or performance improvement plans who have then come off them and been great employees. I've had even more I've just had a quiet word with about an issue and that's been enough.