Noise canceling headphones don't do a good job of canceling the kinds of noise you hear in an office environment, though (conversations, ringtones, people across the room suddenly erupting in loud laughter).

I work in an open floor plan where managers frequently shout and have long conversations next to me with each other.

I use a mix of brain.fm (or similar white noise) and apple AirPods pro. As a combination, they work surprisingly well at blocking out enough noise to let me remain focused on whatever problem.

They are indispensable to me now.

Just be conscious of the effect long-term exposure to constant loud noise can have on your hearing, even if you're able to concentrate. Drowning out loud sound with louder sound is not particularly good for your ears.

mynoise.net does a pretty good "busy cafe/restaurant" noise generator with burbling unintelligible voices that drown out conversations. I used it extensively when directing an animation series where the production staff insisted on having Heart FM playing loudly the whole day.

Agreed. I'm dealing with hearing issues from exactly this type of situation.

Visual noise is as bad as audible noise. What's next, horse blinders?

Well there was the idea of the third picture here: http://theinspirationroom.com/daily/2012/3m-privacy-for-your...

It's from an ad for a privacy screen filter, but unlike that, it works the other way around too, blocking out the world.

That's actually been done already: https://www.dezeen.com/2018/10/17/panasonics-wearable-blinke...

I have fantasized about draping a thick black curtain around my workstation to try to focus. Do you think that would fly?

We had a guy who used his lifted desk to build a little box for himself (out of carboard)

Improv cubicle... yeah. These are sad times when cubicles are a hallmark of the good old times.

How did the management feel about this?

Let's say 'not well'

Noise cancelling headphones don't work for this type of work and gave me tinnitus (ringing in the ears).