I have achieved high levels of noise cancellation by combining over-ear noise-cancelling headphones with earplugs. In particular, I used Beyerdynmic DT 770 M he

I have achieved high levels of noise cancellation by combining over-ear noise-cancelling headphones with earplugs. In particular, I used Beyerdynmic DT 770 M headphones, which already have a high level of sound dampening. Obviously, this is a solution for a few hours of working, not for sleep.