Keep one earbud out sometimes. The best conversations don’t come with a skip button.

Sealing yourself in is comfortable and it closes a door. Most unplanned conversation starts with something small and interruptible, and people will not approach someone who is visibly unavailable, so the openings simply stop appearing and it can feel like nothing ever happens to you. The audio is not the problem, permanent unavailability is.

Leave one ear open in places where someone might actually speak to you. On the walk, in the shop, waiting somewhere. You are not required to talk to anyone, you are just leaving the door unlocked.