I follow tips from memory champions. I use industrial strength earmuffs, a 3M Peltor model, AND soft earplugs. It gives me almost total silence.

The earmuffs are also good as a signal to your coworkers that you are concentrated. They will interrupt you less.

About memory champions training: https://archive.nytimes.com/www.nytimes.com/interactive/2011...

Btw, the author's book is really nice.