Depends on the surgery and how you want to listen.

Ask to have it played in the room? Sure. Want to listen on your own device? We don’t want to be responsible for loss or damage to that device. Want to use earbuds? Same problem if you’re going to be sedated at all, plus there is also the risk of damage to you if there’s metal anywhere.

One of the most commonly used instruments in surgery is electrocautery. A large pad is placed on (usually) a leg and is one electrode; the other is the instrument tip that does the burning. In theory, any metal in the current path could be a point for arcing. This is why you are asked to remove piercings (see your piercer for silicone plugs to fill the holes during surgeries). We don’t want to torch you.

I’m an anesthesiologist. Some of the risks we are guarding against are more theoretical than practical, but until the 1950’s all useful anesthetic gases were flammable and so protocols were focused on not setting the patients or the operating room on fire, and while we no longer have conductive floors and grounding chains around our waists, we do still worry about setting patients on fire (alcohol is still a common solvent for skin prep solutions). And we don’t want to lose or damage your stuff.