High-end headphone brand Audeze recently made an electrostatic headphone that works in MRI machines.[1] No air tubes needed and much better sound quality (and much more expensive).
[1]: https://www.audeze.com/blogs/audeze-journal/press-release-fo...
[1]: https://www.audeze.com/blogs/audeze-journal/press-release-fo...
Very vague explanation of how they work, and that link in the middle - I suspect that is the entire point of the press release.
> The CRBN headphones are integrated into the Lumica AV system from SMRTImage that provides images and movies
Maybe you can get more info out of them: https://www.smrtimage.com/