I don't live in an apartment, but I worked in a super noisy office. I had a relaxation/meditation app that had tons of different sounds on a short loop that could be blended together, such as a fan running, waves crashing, children playing, monks chanting, rain falling, flute playing, a busy city street, etc. I picked the sounds that were similar to the ones I was trying to mask: a high-pitched woman's voice, a deep bass voice, the copier, the noisy door, squeaky carts, etc. I didn't have to crank it to drown out those frequencies. With this app, my brain could put the repetitive noise in the background so I could concentrate.

At night, I have a fan running for noise. In your case, I would want the oldest, noisiest, most out-of-balance fan I could find. You might also try music. The radio doesn't work for me because of commercials and chit-chat between tunes. Good luck.