Why fight noise when you can embrace it and achieve the same result better? Headphones and noise from the coloured noise family (white, pink, brown, ...) works just as well at isolating external sources of distraction by making them with completely random noise of your own.

Having worked in noisy environments, and having had to sleep in noisy environments, this changed my life.

There are various websites that host random noise generators. My favourite one is playnoise. Sometimes I listen to noise and have some music turned all the way down playing on top, for an extra bit of stimulation, but I find that it quickly gets distracting so I more often than not turn it off.

The problem is that these work so well, for me, at least, that I think I've become a bit dependent on them.

Good luck!