How do MRI Headphones work? (2022)

To help pass the time they have you wear headphones so that you can at least enjoy music that you can barely hear over the thumping of the machine. The only headphone tech that I was aware of or that I'd ever really considered was the typical diaphragm and magnet drivers "Driven" by electrical signals traveling down a stranded copper wire. I'm in an MRI. I'm not allowed to have any metals or magnetic materials on me. Why would these headphones be OK? Was it the same principal as a microwave? In that metals don't really have the effect you imagine they'd have? Surely not - MRIs use magnetic resonance not radiation like an X-Ray or CT and certainly not microwave radiation. Then at the end of the MRI I noticed that the "Cable" of the headphones was kind of "Thick". Instead of magnetic drivers that would otherwise pose a problem with use near or inside of an MRI, there is no wire and there is no driver. The headphones are nothing but a cup with a tube extending from them that leads from the headphones away from the MRI machine into another room where the drivers are located.