Previously, very similar.
Wondering if advice has changed three years later.
I live in New York City and have lived in the same apartment for over three years. My downstairs neighbor has pounded on my door on four different occasions over the course of this time to complain about noise coming from my apartment. Her issues are footfalls and doors opening and closing. The first time I was genuinely super apologetic, bought slippers, which I now wear all the time, and became a lot more mindful of the noise of my footsteps. The second time I was even more apologetic and gave her my cell #, telling her to text me when the noise got troublesome so that I could figure out exactly what was bothering her and stop (and prevent her a trip upstairs, hopefully before she got to the point of anger). The third and fourth times I was polite but dismissive -- "I'm doing all I can; I'm sorry; I've told my roommates (etc)." FWIW, she's never texted me -- she seems to wait til the point of rage, when she visits in person to yell.
I just awoke to a profanity-ridden tirade slipped under my door at 3 AM from "the downstairs neighbor." While lengthy and mean, it doesn't offer any more information as to the exact nature of her complaints. So I assume again it's footfalls and doors opening/shutting. Her bedroom is under my roommate's bedroom -- it's true, he's a night owl -- and I told her the last time she visited a few weeks ago that he's moving out at the end of the month (he is).
My roommates and I are quiet people. We don't watch TV (it's broken), listen to music, or have parties or kids. We walk around in the course of normal activities and open/close doors. That is all. I understand that even these sorts of noises can be magnified and near-intolerable under urban living conditions (my bedroom is next to the stairwell for the building, and I can hear every single person run up and down it 24 hours a day/night as if they were right beside my pillow), but I feel that's sort of par for the course if you live in a not-very-nice (ie not soundproofed) apartment in an urban environment. I myself have been sleeping -- happily -- in earplugs for years.
What is my next move? Talk to the landlord? Talk to her? Pretend this never happened? My lease is up in a few months, and even though she's annoying, I'd like to stay in this apartment.