I've seen quite a few adverts for these recently, claiming to be particularly good for blocking noise:

https://www.flareaudio.com/products/isolate-aluminium

Has anyone got any, and tried using them on an aircraft? I sometimes try sleeping with noise-cancelling earphones on, but they're quite bulky and usually end up down the side of my seat, so these might be a better alternative. I'm a bit skeptical though, and imagine these might turn out just like those yellow foam things they usually give out for free...