The Etymotic noise isolating earphones?

I just replaced a pair of 10yo ER6i 'phones with ER3XRs. The have not only a very flat frequency response and excellent clarity (great for classical, jazz, vocals, and so on), but also (and more relevant to your situation) a noise reduction ability of 35-42dB.

I put these in at work in our very loud open office environment and I cannot. Hear. Anything. Not the person on the phone pacing in front of my desk, not the yelling of the interns, not the Sonos. Just sweet, sweet music.

Much better than active noise reduction, which is much better to block out droning noicse and can actually enhance your ability to hear external voices and such.