Well, you've tried the two best options, talking to the neighbor directly and going to the manager. I'll bet the manager is getting a lot of complaints, if the music is that loud.

At this point, I think your only option is to see if the town you live in has any noise ordinances. If they do, and they cover daytime hours, you may be able call the police when the noise gets really loud.

Does she quiet down after 9 pm? If she doesn't, call the manager and call the police.

And if that doesn't work, I'd wait out the remaining months of the lease and move. Or check with the manager to find out what the penalty is if you leave your apartment early. I know it stinks that you should have to move, but that may be the only solution. And if the powers that be learn that good tenants are leaving because of one noise-maker, they might start to crack down on the problem tenants a bit more.

Agree with camlam.
Going a bit further...

This appartment itself is just terrible, there's a heavy roach infestation in the trash chute and our bathroom is growing mold.

I was going to suggest some things to follow through on that, but rereading again, you've mentioned everything was fine for 9 months till noise started, and now the mold and roaches are bothering you as well?

Have the bugs and mold been there all along? If so, 9 months into the lease is late to address it, kind of knocks your credibility. But you can try.

If bugs and mold are newer developments, I'd suggest addressing it immediately from that angle. Because I'm about to suggest you consider moving. More on that below...

Before suggestions, details on the mold. Where is it located? If it's in the tub area, you're only going to get a response that it needs to be cleaned regularly with a product with bleach or something like Tilex Mildew Root killer. It only takes about ten days of not cleaning before mold can appear in a tiled area. (I had one rental it was so bad in tub corners from not cleaning regularly I had to pull all caulking out and replace, mold had gotten under the caulk by that time.) But if mold is on a ceiling area, or a drywalled wall, or behind a sink, that could be indicative of too much humidity (exhaust fan is needed) ~or~ there's a leak somewhere (plumbing, overhead unit if there is one, roof above if there's no one above you). It's permitting moisture to seep through walls. If that's the scenario, you don't want to live with it and mgmt needs to be alerted because if they don't address it, it will only get worse and cause higher cleanup/repair costs.

I'd suggested something in writing (Certified, so it has to be signed for) to mgmt/LL. This does two things: creates a paper trail as a record and shows you made an attempt to resolve with LL first. Don't make threats or be aggressive, just be businesslike and point out the issues and the health concerns. (Mgmt doesn't necessarily know it's there if you don't tell them.) If there is no response to your letter or action taken, then you might want to consider calling the health department.

Approaching from this angle is going to prepare you for a move. If you're on a longer than annual term, health department violations not addressed are a legitimate reason to get out of a lease early (and where your written record of communication will come in handy).

If, on the other hand, you're on an annual lease, I'd encourage you to start looking at other places soon, and not renew your lease there. Would it be too difficult to start thinking about a move? Imagine funds are tight with your DH in med school, but is that an option? I generally don't like to see "just move" as a suggestion, but if you're on an annual lease then you're nearing the end of your term and renewing it could feasibly lock you into the chaos that much longer.

Your lease probably says you have the right to quiet enjoyment. That can be a tricky one to address, because noise is subjective. What bothers some won't phase others. But honestly, if mgmt is saying they can't do anything unless it's after 9PM, then odds are they won't be doing much about it. So maybe you can use the remaining term to look for a new place? Because if this woman is a screamer, has permitted her kids to scream and be disruptive, and she's comfortable displaying that behavior right from the get-go at move in, odds are not much is going to change those behaviors unless she's removed from the premises. Mgmt is going to need a really strong case to prove in court in order to evict someone from their home, and noise complaints usually need police visits with written reports as support documentation. Without that, it's one's word against another and very difficult to claim and prove.

As a former frequent migraine sufferer, I feel for you (and could it be mold is a trigger?). LLs get this too. One of my rental homes has a newer neighbor like that. She's a real nut case, and the driveways are right next to each other. I will have that house on the market soon and that neighbor is going to be a deterrent to renting, she's that obnoxious. I learned from surrounding neighbors the police have been called several times because they (mom and teen kids) get out on the front lawn and scream, yell, teens argue and swear at each other, I hear it has gotten pretty out of hand. Neighbors don't appreciate all that going on in front of their small children, it's a very family friendly neighborhood. So police come, settle it down, and leave. I stopped there the other day to do a repair in prep for renting and she was on the lawn bellowing at her kids. But she wasn't breaking any laws, just being obnoxious. I figured swell, I'm going to start showing this place, it's warm weather outside now, and any prospective tenants are going to see what's next door. So it can be very frustrating from a LL point of view, too!

Drseattle: I'm going through pretty much the same thing that you are right now so I feel for ya. I have extremely loud, rude & obnoxious upstairs neighbors, which is far worse than having them across the hall. These idiots moved in almost a year ago & we've had nothing but problems. They make all kinds of noise 24/7. They have a bunch of people living up there that aren't supposed to be. They usually have 4 to 6 little kids up there daily who bang on the walls, stomp, run & pound on my ceilings & throw loud screaming fits. These people never seem to sleep & these kids are up at all hours of the night running around. Take last night for example. They were still up running around, pounding & screaming at 2am. I almost had to call the police on them AGAIN. We get woken up all the time & never get any peace & quiet. These people have loud, obnoxious guests over late at night. They have also started vandalizing my car, stealing our mail & they have their friends harass us by pounding on our apartment door late at night & running off. I know it's them pounding on our door because I've looked out the window & seen them running away. However, I can't prove any of it. I've talked to the property manager about this crap & she refuses to do anything. She told me to move if I'm not happy & I've lived here a lot longer than these morons have! Not fair at all. I've also called the police & they can't do much but tell them to quiet down. I'm at my wit's end here so I'm moving in the next month. I've tried everything else & nothing has worked so I have no choice. I can't keep losing sleep like this & I treasure my privacy & my peace & quiet, both of which have been taken away from me.
You've already talked to your landlord who refuses to do anything, so try calling the police anonymously when there's loud noise past 9pm. If the crap continues, you may have to think about moving whenever your lease is up. It seems like the bad tenants always win in situations like this & it's very unfair. People like this who continually harass their neighbors & make their lives miserable should be the ones who are forced to move out. I'm relieved that my troubles will soon be over because I've had more than I can take. Best of luck to you in your situation! :)

Move.

I know that's not really the answer you want to hear, but that's the only solution I was ever able to find that would work for me when I was in a situation like yours. If your landlord will do nothing, and talking to the person does nothing, then you're really stuck. People basically can make a ton of noise during the day, and get away with it, and that's just reality.

Make sure the next apartment you find has great soundproofing and a layout that minimizes wall contact with neighbors. And if possible, start saving up for a house -- that's honestly the best thing in the world. No shared walls, minimal contact with crappy neighbors (generally).

thegrinch17 said-"They have also started vandalizing my car, stealing our mail & they have their friends harass us by pounding on our apartment door late at night & running off. I know it's them pounding on our door because I've looked out the window & seen them running away. However, I can't prove any of it.

I've talked to the property manager about this crap & she refuses to do anything. She told me to move if I'm not happy & I've lived here a lot longer than these morons have! Not fair at all. I've also called the police & they can't do much but tell them to quiet down. I'm at my wit's end here so I'm moving in the next month."

I'd be calling the property manager whenever these clowns act up. Let the post office know that they are messing with your mail. Thats a federal offense. Good luck at your new place.

Dreamgarden: I've tried reporting them numerous times to the property manager but she won't even answer my calls or return them anymore. She wants to live in her own little world & collect the rent money every month, but she doesn't care at all what the other tenants are doing. I've tried everything that I can & am sick of being harassed & losing sleep so I've decided to move. This will solve all of the problems that I've been having here & I won't have to deal with this crap anymore. I've found a much quieter place & can't wait to get out of here. I'm just counting down the days! :)

I used to have noisy indian neighbors downstairs. They were quiet at first but then the kid started playing electric piano, jumping, playing with a ball, on and off all day long. 4-5 in the morning the woman was cooking up a storm in the kitchen. Their tv was so loud i had to get rid of mine because i could not hear it. Lease agreement states i'm entitled to piece and quiet, the super didn't want to get involved. the super told me i can do anything (within reason) 8am-10pm. I don't do anything, i don't make noise. I figured i will do to them what they do to me only worse. They were gone within months. I'm also researching infrasound.