Open-plan offices are absolutely maddening, I get pulled out of my thoughts constantly, and there's no effective way to shut it out. Earplugs aren't enough, and with headphones I would have to play music so loudly it would be annoying my colleagues, just in order to cut out the constant noise. We have so-called "focus rooms", but 1) there are far too few of them, and 2) they're supposed to only be used for short phone meetings and such.
I raise this with my manager every time we have a "pit talk", as they're now called. But there is seemingly nothing he can do.
Furthermore, administrative controls (headphones) for what is actually a safety and health problem (excess noise) are the solution of last resort from a health and safety perspective. A good health and safety person would advise structural mitigation, not forcing everyone to put on personal protective equipment (headphones.)
When open plan offices can regularly burst up to 95 dB (yes, I took in a meter and measured the last one I was in) and are often 65 dB when they are "quiet", noise is absolutely a health and safety issue. Constant noise, even if not immediately damaging to hearing, can cause increased stress and other physiological issues.
I've also tried earphones with music, but I can't work like that for long, I just start listening to the music instead. I need peace and quiet.
And of course there's the issue of visual noise as well.
https://www.amazon.co.uk/Bio-Ears-Silicone-EarPlugs-Protecti...
I split one in two and use them that way, I've gotten to work with them in before without noticing, maybe worth a shot.
I bought a box of 100 pairs of Bilsom 303 plugs a couple of years ago, for motorcycling. The whole box was $40.
They are very ineffective against voices! Passive insulating headphones are much better.
https://www.sfgate.com/news/article/Bose-headphones-have-bee...
I think the awful smells I can't escape are worse than the noise at this point.