Reducing sound through a single wall only...

[princeplanet]

OK, so after building 2 studios, I know that RWAR is the only way to go for sound attenuation, every surface properly decoupled. I've never used sound clips because I haven't needed to. But we have just purchased an apartment where the masonry wall between apartments is still letting through the sound of voices in a room I'd like to set up as a home studio to do low level mixing and maybe some acoustic guitar recording.

I can hear a TV and human voices from the other side, so I will assume they can hear the same from their side. Anyway, let's assume the concrete slab floor is not a problem, and that the ceiling is too costly to consider sound clip treatment. That leaves the main party wall and the 2 side walls (that do not adjoin to the neighbour). My question is: If I use something like whisper clips to decouple the party wall (which has plasterboard on battens over the masonry core), without doing the same to the ceiling and side walls, how much reduction should I expect?

I should add that when I put my ear to the walls when hearing voices from the other side, the transmission through the non party wall (the side wall) is around one quarter the strength of the transmission through the party wall. The other side wall actually is a window wall and has little to no sound transmission for some reason... Anyway, obviously by decoupling the main common wall (party wall), it will not decouple the side wall so presumably I'd still get some transmission there right? Would I be taking down the existing P/B from the party wall and applying the sound clips to the bare studs, or is it OK to fix the sound clips directly onto the existing P/B, and then add a layer or 2 of new P/B ?

If I took away the existing P/B then does that create less direct contact with the side wall (no direct plaster to plaster transmission)? Or is the transmission still occurring through the stud wall connection (wood to wood?). Naturally I will be making sure to stuff both walls with 60kg/m3 polyester insulation, if they're not already.

As stated, I have no experience with sound clips, so have no idea what to expect. I'd appreciate ay thoughts, Thanks in advance!

[DanDan]

If you were to replace the existing stud and board, you could optimise.
You could identify and seal any leaks.
Apply a layer of render to gain a few dB at least.
Create a bigger gap, again gain a few dB.
Fill the gap with fibre, not compressed, but fully filled, this can increase TL by 9dB or more. Light partition roll or blankets work the same as dense batts here.
Is there enough space to do independent studding?

[princeplanet]

If you were to replace the existing stud and board, you could optimise.
You could identify and seal any leaks.
Apply a layer of render to gain a few dB at least.
Create a bigger gap, again gain a few dB.
Fill the gap with fibre, not compressed, but fully filled, this can increase TL by 9dB or more. Light partition roll or blankets work the same as dense batts here.
Is there enough space to do independent studding?

The room is small, so was hoping to lose only around 50mm (2 ") all up if at all possible.

The wall behind the plaster is meant to be 100- 150mm cement (or brick), so no room for new studs...

I guess it has to be sound clips on battens. If I had to replace the battens, could I glue some rubber behind them? Or is that redundant because the sound clip decouples anyway??

[gullfo]

the challenge to the single wall approach will be when you do increase it's TL, your flanking levels will become more apparent - on both sides - ducts, pipes, frame/wall bridging etc. via floor and other walls, plus any windows on the same side can be conduits between living spaces. grab yourself a mechanics stethoscope and listen to the walls and floors, pipes, ducts, windows, etc to determine how sound is being transferred. if on good terms with the neighbor, consider running audio in your place and listening on their side to determine routes.

[princeplanet]

the challenge to the single wall approach will be when you do increase it's TL, your flanking levels will become more apparent - on both sides - ducts, pipes, frame/wall bridging etc. via floor and other walls, plus any windows on the same side can be conduits between living spaces. grab yourself a mechanics stethoscope and listen to the walls and floors, pipes, ducts, windows, etc to determine how sound is being transferred. if on good terms with the neighbor, consider running audio in your place and listening on their side to determine routes.

Yes, just one side wall is flanking some sound, but around 25% of the level through the party wall. This flanking would surely decrease if the party wall is decoupled as the plasterboard will no longer be in direct contact with the side wall. Obviously the studs may still transmit, but hopefully it may be negligible? If I could improve midrange frequency by 6 to 8 dB by just decoupling the main wall, I would think it worth the trouble (and cost! ).

Can you suggest a poor man's stethoscope? A funnel on the end of a hose?

[gullfo]

Amazon the stethoscope is cheap enough

[DanDan]

I must get one of those Mechanics Stethoscopes. Clients are not too impressed with my Drum Stick in my Ear.
A client here got a company to come from afar to install rubberised studs, 50mm gap. 10K Bucks. No audible change.
We have a material called Calibel here. Plasterboard with semirigid fibre attached. They glue or dab and daub it to the brick wall.
In any case if you are trying to decouple in that 50mm, try to find something that actually works in terms of the resilience, floating.