These are NOT the swivels you are looking for...
Assuming you have a muffler on your bike you can either listen to wind noise or you can listen to music. Virtually everything else gets blocked out at any speed over ~28mph.
Wind noise above ~28mph will cover up important road sounds, like a car overtaking you just as much as earbuds will. Sounds that would improve your safety if you WERE able to hear them.
Of course an open exhaust will drown out just about everything.
So the only time you REALLY want to be careful with music, and perhaps reduce volume, is at lower speeds in town, where wind noise would NOT prevent you from hearing important sounds, cars pulling up right next to you, horns, people yelling, etc.