This unfortunately is a very bad problem for me - sort of. My issue is that my downstairs neighbors have a very loud airconditioning unit which is installed in the ceiling. I have tried approaching the problem from every conceivable angle including of course, talking to them. And nothing works. They are absolutely intransigent. Will not budge. Any vibration dampening advice is appreciated!

I recommend carpeting and regular curtains. Hard surfaces like hardwood floors, windows, and drywall reflect the sound waves. That is why most apartments have carpeting.

...or you could also try a white noise machine.

Rugs rugs rugs! A big thick one for the living room and another in the hallway. You can also hang a thick curtain behind your bedroom door and pull it shut when sleeping or studying.

Anything fabric &/or plush will help. Rugs, curtains, fabric furniture, sofa pillows, etc. Breaking up the space with a room divider might help too. It can't hurt to try it.

What about textiling the ceiling? It can be difficult to utilize in a rental situation, but if you are short on wall space and are able, a nice hippie tapestry type thing will hang like a lovely pillowy tent-like ceiling. If you are more demure than that, though, a few layers of sheer white curtain panels will be largely unnoticeable, and they are still lightweight enough not to require any major hardware.

As an indirect-lighting bonus, throw some Christmas lights up there and it's all twinkling stars at night.

In addition to curtains and area rugs, which will help to absorb noise, you can add foam or cork panels to the walls along the hall to help absorb noise on its way down the hall. I think AT had a post about sound-dampening tiles in a post not long ago, that looked like fabric covered panels, lining the walls of a media room. Something like that may work to muffle the noises coming from the living room when the TV is on.

If you have frame-less paintings with room between the canvas and the wall (think Ikea or blank canvas frames from an art shop) you can glue some acoustic foam to the wall behind the painting.

Also, for speakers, decouple them from the floor with a piece of MDF supported by dense speaker foam blocks. You'll get less vibration and better low frequencies for fuller sound.

PS: I think it's 'damping'. I can't quite figure out how one makes sound wave wet/damp. :p

If you want to reduce noise build-up within the living space, try a stretch fabric system with 1" to 2" thick semi-rigid glass fiber backing on your ceiling/walls. They are relatively monolithic. Not cheap, but looks better than the average fabric wrapped panels. Also make sure the fabric is relatively acoustically transparent. You can get a general idea by putting a sample fabric under a spotlight and seeing if light goes through the fabric.

Check out:
Novawall - stretch fabric
Clipso model 795A - canvas like that can even have photos printed on
Newmat - if you want to splurge a bit. I think Ralph Lauren used this in his fancy car garage (http://newmatusa.com/newmat/2400/main-projects/ralph-lauren-garage.html)

Remember, the key is the glass fiber backing, which provides the sound absorption. The more surface area it covers, the better.

Doing this will NOT help block noise form the living room to the adjacent spaces. It just provides a more comfortable environment when everyone is hanging out in the living room.

Hi again! If you are more concerned about blocking some noise to your bedroom, say at the end of the opposite end of the hallway - that's a bit trickier. You can do the bookshelf barrier as long as it's solid, and cuts the line of sight. What it sounds like is that you need a door to your living room?

I recently saw a wall completely covered with cardboard egg cartons tacked edge-to-edge on the wall to dampen noise. It was very industrial looking, but I imagine it could be put up then covered with something more attractive, creating a honeycomb barrier between two rooms. If you are renting that solution would be cheap and if done carefully wouldn't damage the wall too much. Those cartons are light enough that you could affix one with a single pushpin.

Here's another thought -- when people are trying to sleep or study, the people in the living room could TURN IT DOWN!

Just sayin'...

I agree with the white noise. I sleep with a small fan on every night. I got used to it when I moved in with my boyfriend and he needed it to sleep. It drove me crazy the first week, after that I was hooked. Seriously, I turn that thing on just before I go to sleep and I cant hear much of anything going on around me.

I used one for all of my kids to help them sleep without a noisy sibling waking them up or a dog barking etc.

I cant sleep without it and bring it with me when I travel or sleep somewhere else.

Yes, I also have a small 8" clip-on fan on a bookshelf near my bed that I turn on to drown out sounds. Works great.

@Borage

I had the same problem with a neighbours air con - they were running it all night and it was basically the same level of noise as a lawn mower - which is pretty hideous to sleep to. But I did some searching and in my area there is a law that states you can't make loud noise after 10pm and this included using aircon. I'm in Melbourne but I'm pretty sure it would be worth you looking up what laws and regulations are in your area. I just wrote a note saying the noise level wasn't ok and that the law states blah blah and they complied. If they didn't I was quite prepared to take it further.

Good luck!

Would it help to put something on the outside of your bedroom door? Essentailly upholster it with foam and wrap it in a decorative fabric. Some buttons to give it a tufted look, could be quite stylish.

building on rmsu's idea, why not hang a tension rod at the doorway between the LR and hall with a curtain on it. just pull it across when you want to cut the noise down.

In my apartment I have these wall heaters that passes from my living room wall to my bedroom. The sound echos right through that thing! I draped a sheet over it on each size and it helps a ton. It still awkwardly takes up space though

Thank you very much, Raven. The thing is, it's this tortuous vibration hum noise (sounds like there is a jet engine from some distance away, but a jet engine nonetheless) which does not actually exceed night time noise levels (to my knowledge). Yeah, I've talked to one of the guys, and basically gotten nowhere. I *wish* there was a law about a/c units at night, but unfortunately in this country we have a raging a/c addiction going on right now, something that is making us more and more intolerant to normal temperatures - they use the a/c unit even if it is 60 degrees Fahrenheit outside. Ridiculous. I'm not really an extremist, only at the end of my tether. Rugs, fabric, rods, screens - no those don't work. I have had to resort to a white noise (actually it's called brown noise) and it helps but it also keeps me awake sometimes too.

Threaten to take away people's airconditioning in the US and you will have a riot on your hands lickety split!

Borage, sorry for the rant that's about to come. It seems when anybody comes into the U.S they get a raging A/C addiction worse than the locals! I had a roommate from Bagdad, Iraq who wanted the apartment to be 63 degree F during the summer. I flipped out when I passed by her room and saw a quilted comforter on her bed, no wonder she wanted a frozen wasteland when she cocooned herself every night like that. So it was a constant battle over the A/C because I'm comfortable at 80 degree F. Then I had a roommate from Germany who also wanted an indoor tundra and I just about lost it and told him to "man up" and loudly wondered why do I keep getting all these wusses. The next set of roommates I interviewed I asked them what is their comfortable ambient temperature. The problem is they all said what I wanted to hear because my rent is cheap and the location is in prime higher end neighborhood. My current Filipino roommate is doing her best not to turn on the A/C as much and I'm doing my best to be less of a jackass.

Borage - depending on where you live there are noise ordinances that may apply to the outdoor equipment noise.

Lady J - you need mass to block sound - curtains don't have much mass, so they are not as good as something like a bookshelf.

Sound masking noise is good for some things, and plenty of people use it to fall asleep in urban areas that are too quiet. It works by making the signal (TV, whatever) lower in resolution when it reaches to you. Think of a 'fog' that blocks your sight to something far away. It's best for speech frequencies, but not very good for music with a lot of bass.

Zenezie - Thanks, and feel free to rant away! Perhaps it is the new arrivals that are fueling the overuse of airconditioning. And I swear, it is lowering our tolerance for the outdoors!

RMSU, also thanks to you. The thing is, it's not an outdoor unit. It's indoors, and it's installed in the ceiling so the noise and vibration come up from my floor since I am above the offending unit in my building. I use brown noise to block it. but it's lasts 4 hours (I guess I could extend it, but I worry about wearing out my MP3 player and dock station) and so when it goes off, and the super loud aircon unit below me switches on - well, I wake up.

For me it just comes down to this: should our apartments be repositories for other people's mechanical noise?

Think padding.

Carpets, drapes, upholstered furniture, quilts hanging on the wall.

The padding absorbs the sound.

No, unfortunately that did not work Chieromancer.

Borage, I know that you have stated you spoke to the tenets below you but have you asked them to come up and hear the noise? Otherwise is it possible to add window air conditioner units in your building? I ask because even though it would cost you you could offer to split the cost of a window unit for the below tenets bedroom. Also try a fan in your room to make noise. Hubby and I can't sleep in our house any day of the year without our fan going so that we have that noise to fall asleep to. Might work for you.

May try those interlocking foam gym pads on the floor, and then cover them with a rug?

Thank you Arkay. That is the onething I have not tried, and have been wondering about.

Hate to state the obvious, but can you install a door on the room? All the curtains, carpets, etc. in the world won't make much of a difference is the sound has a direct escape route into the hallway.