Hi all.

I have a simple and very urgent question.
If you follow this link, you'll see pictures of my room, which has double brick rendered walls...

http://www.avsforum.com/avs-vb/showthread.php?t=1117258




It's a funny shaped room. Its front and rear walls aren't perpendicular. But on average, there's 4 metres between them, and a glass door on the right which leads to the balcony.
The main listening area is about 3.7 metres wide, with an adjacent entrance to the front door & kitchen adding another 2.5 metres.

The neighbour's apartment is right on the other side of the projection screen wall.

Behind the pull-down projector screen and curtains, I've stashed a jigsaw puzzle of packing foam and styrofoam against the wall.
This serves 2 purposes...
1. It helps to reduce sound transmission to the next apartment (most importantly).
2. It helps to deaden the room a little more.

(Beneath the screen, I'm using a black carpet-like material called Wonderwall, which is tacked onto the foam. This will remain.)


But now, I'm needing to replace the foam with something else.

As you can see, there's only so much I can do.
* For one thing, it's a rented unit. So I can really only tape some sort of material against the wall.
* Ideally, I just want to gaffer tape the material to the underside of the projector screen headbox and let it hang over the wall.
* On either side of the curtained area, I'm wanting to leave that area uncovered. So sound will always transmit unimpeded.
* I have no more than 5 cms behind the screen

After looking into a few materials, I bought 7 square metres of this stuff..
POLYROLL 32/25 BLACK, a third of the way down this list...
http://www.peaceandquiet.com.au/price_list.htm


Now, holding up some of this Pollyroll material against a speaker, I notice that it's blocking relatively little sound from coming through, compared to styrofoam, cardboard, etc.

I'm wondering if I should swap it for something more like this barrier material...
http://www.peaceandquiet.com.au/NOISEBAR_BASE_PQ.pdf

...although I was advised that absorbtion on my side would be the best way to stop sound transmission.
A barrier material would be mostly useless as the sound will get in on either side anyway?



What's the best possible (and most cost-effective) material that I could use in this case?
As it's concealed, colour and ugliness are non-issues.


Two other points:
* The left/right main speakers have front & rear bass ports, and go down to around 25Hz.
* I have a slight bass boom problem, which I'll be helping to alleviate by making some bass traps for the corners.



Thank you very much, in advance!

Your problem will be bass frequency's witch will pass trough wall like hot knife trough butter. There is nothing to do to help it from passing without modyfing the structure. My advice would be to treat the more corner you can with absorption. This will give you a better bass response, witch will make you turn down the volume of the subwoofer. That is the only without modifying the wall and wall structure.

Barrier can be nice for end of bass, mid and high, but in movies there is a lot of bass and this is what will make your neighbour's crazy.

Unfortunately, absorbing materials will not do anything to reduce sound leakage into an adjacent apartment. If you are renting, I'm afraid there's nothing you can do to reduce leakage without voiding your lease. The main problem with leakage is usually low frequencies, and those are the hardest to block. You might be able to reduce leakage at midrange frequencies a little. But I'm not optimistic.

--Ethan

Thanks for the responses.

* It's a 7.0 system, with three full-range mains and no subwoofer (anymore).
The left and right towers are front and rear ported. The centre is double-front ported.

* If I hold up various materials between me and a loudspeaker , they will all block the sound to greater and lesser degrees, and mostly in the midrange and up. Bass is largely unaffected. The packing foam I had previously seemed to transmit noticeably less, and I imagine its absorbtion wouldn't be too bad either.
Surely, each of these materials will have some effect when laid against a wall, however slight?

* Is it fair to say that less sound will be transmitted if more of it is being absorbed on my side, whatever the frequency?
When I make and put in some bass traps, and succeed in reducing booming, summing and standing wave issues on my side, then there'll simply be less of that bloated bass to escape, correct?

-effect in the room itself, not for sound transmission
-no, not really
-no, but bass will become so much more present that you will lower the volume of the bass yourself. Then there is less bass in your neighbour's appartment.