Does piano soundproofing require floating walls? Getting conflicting answers from professionals

Question

I have just placed a new hybrid piano in a small 9x13 room in my apartment. I want to use the room for playing and for singing. Costly steps have already been taken, and, much to our dismay, we still need much improvement. At this point we have about $5000 left for the whole project.

The room's only direct connection to neighbors is through the floor.

A soundproofing company recommended MLV for the floor, but, since we still want hardwood, we paid $4200 (NYC) for the hardwood floor to be removed, 12mm thick Ecore installed using sound-dampening Bostik glue, and new hardwood floor again using sound-dampening Bostik glue.

Someone went to the neighbor's to test it, and alarmingly the sound is still quite present. (We don't have a solid before-after comparison because we only used a recording to test before).

Now: soundproofing company came back and said the next step is to install 1.5" thick melamine tiles on a portion of the walls. We need to decrease the reverb in the room, but he says that this will also assist somewhat with the transfer to the neighbor, since there will be less sound to transfer.

I have a terrible feeling it isn't going to help as much as I want it to.

So, I asked a soundproofing specialist, and he said this, which discouraged me:

"By simply soundproofing the floor does not stop flanking noise from the 4 walls in the room sending sound to the downstairs neighbor.. What I do not see is decoupling for low frequency and lots and lots of Mass. Ecore is for footfall and impact but is not going to perform as you would expect for low frequency. This requires far more attention to decoupling and mass."

I told him that we are trying to manage this without opening up the walls.

He said, "Without decoupling, your chances of reducing low frequencies becomes minimal, which would require opening the walls or take a risk on a triple leaf system.

"As for the absorption aspect, yes if you address corners and cover the majority of the walls you would reduce some of the sound pressure levels and therefore reducing some of the transmission.

"The real question would be how thick would you need to go to see cost vs reduction..

"Are you handy? if so maybe a DIY 4"-6" thick mineral wool or cotton fiber panels. if you make your own, you can add a septum of mass loaded vinyl, which would give e bit more help in the low frequencies since you do not have much mass on the walls."

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It's becoming apparent to me that there are lots of differing opinions on this. I wonder if crowdsourcing here on this site could help me? It doesn't have to be SILENT by any means, because the neighbor is understanding. And yet, for a total of $9000, even in NYC, one would think that a lot could be accomplished?

Answer 1

The basic reason you are getting ripped off here is because you are not doing your due diligence.

If your contractors and consultants won't guarantee a sufficient level of sound reduction, they can recommend whatever looks like it will make them the biggest profit - which explains why you have lots of different proposals none of which have worked so far

There are companies (at least, in the UK) who are quite happy to guarantee levels of sound reduction like 60 to 70 dB which would make a piano close to inaudible, and build something that is fully transportable if you move house - not "something that might work if you get lucky, permanently glued onto the floor and walls."

This is what serious soundproofing of a house room looks like:

http://www.amadeus-equipment.co.uk/case-studies/jazz-pod-in-town-house/

Note the scale of this - the soundproofing involved installing two tons of structural steelwork, not a few bits of wood and tiles and some glue. On the other hand, the installation time was only a couple of days.

Doing it right won't be cheap - but doing it wrong yet again is just throwing good money after bad.

Answer 2

alephzero's answer is pretty spot on, but from reading your question I think you are buying the wrong kind of product.

In my read, you asked to help quiet the piano for your neighbor. Which was done. You may have even inadvertently asked for the best sound reduction X amount of money can buy. It does sound like you asked for the best options that doesn't require certain kinds of modifications (opening the walls).

When you start doing that, you get some pretty odd results. The contractors may be doing their best, in their opinion, given your requirement, and their perceived requirements.

For example, if you came to me and said. I need something to hold the 20oz of water. I would hand you a used soda bottle. Then if you said, "it can't be plastic" I might be able to hand you a glass bottle. Then if you said "it needs to weigh less then 100 grams" I would be kinda stuck and might hand you a big paper cup, with no plastic lining of course. So now you can :

• hold 20 oz of water
• it's not plastic
• it's less then 100 g empty.

I have done my job, and I feel pretty good about it too. I met your odd requirements. Good on me. However your left feeling let down because your new water holder is fragile, leaks, and seems too expensive for what it is.

My point is that your kind of approaching the entire problem the wrong way. I suggest going to a new company, someone who doesn't know your space or your needs, then tell them your main goal. I want to play my piano and I don't want the downstairs neighbor to hear it.

Then see what they recommend. Get a quote, and as alephzero suggested, a guarantee, then see if any of your current materials/install is useful.

Also keep in mind that you're not going to be able to stop all of the sound. It may be cheaper to rent a second space than to try to sound proof that one.

Answer 3

Was posting this as a comment, decided it might even be an answer:

You could build a box around the piano and decouple it from the room that way instead of trying to decouple the room from the apartment building. Depending on the room size, even a floating platform and lucite cage as used for drum kits may be the more cost effective solution. You can get isolation booth kits and parts of various sizes. They are often used at trade shows to demonstrate products in a noisy environment. Do a search for sound isolation booth or drum isolation booth and you will see many examples.

Answer 4

Sound travels in buildings through either the structure or air, you seem to understand that. Air borne sound travels through leaks in the structure, air ducts, etc. Floors are almost never perfectly sealed; walls have lots of openings. Even though the floor may now be isolated to a degree, structure borne sound (sound in your apartment vibrating the floor, walls and ceiling) can travel downward through the walls and even ceiling. Consider your piano's legs; if they haven't had an isolating base installed their small contact patch will transmit sound very easily through the floor. Not sure how heavy your piano is, but floor contact of any kind easily transmits sound through typical joists. Try going into the apartment below and listening carefully to what you hear when your piano is playing; do you hear the entire keyboard or just certain notes? Adding vocalists will change things considerably. An acoustic analysis using microphones and software in the lower apartment would help a lot to determine how to isolate yours; the best contractors will do this. As stated before, be sure you clearly lay out your expectations and understand how your problems will be addressed. Get references and contact them, visit them if possible.

You've done some of this, the sound proofing specialist's comments are right on the mark; your floor treatment can't do much, adding absorption to the walls will change the room's acoustics, which must be painful as is, and make it hot, but not help much with the neighbors below.

Air borne sound transmission is not terribly difficult to attenuate considerably in a residential environment but structure borne transmission, the annoying upper bass whump whumps, and resonances can be very difficult. Regardless, high isolation will require a room inside a room approach (recording studio, e.g.) and starting with a small room may result in something the size of a closet with a low ceiling. What you want to do is easy for a contractor who understands acoustics; difficult for one who only knows how to apply sound treatment products.

Depending on how loud you intend to perform, your plan may not be possible; consider looking for somewhere else to practice; you've spent a lot already and don't seem to have achieved significant attenuation; renting or leasing a small venue elsewhere may be the way to go. Have your friends chip in!

There isn't a simple solution to your problem; you can do everything recommended and still have nasty whump whumps (love that silly term!) downstairs. First thing I'd do is bring back the sound proofing specialist and have them lay out a plan for your goals. At some point ask "Can this be done?" Then sit down when the cost is presented. JK. Good Luck!

Answer 5

It's less a matter of opinion than it is the degree of soundproofing different people expect. The fundamentals are just physics and fairly predictable.

The "specialist" is correct in that that's how you'd go about it ideally for a recording/practice space. The concept is typically to sort of build a room within a room (decoupling, as was mentioned) in conjunction with using as much mass as possible in the walls.

But that can be expensive especially if you are just trying to make a room quieter from normal day-to-day noise like a neighbors TV or street traffic. It doesn't take such an extreme approach for that kind of noise. I'd guess that that's the bulk of what said "soundproofing company" does.

So it's not really a matter of who's right. It's more of what approach is good enough and at what cost for your particular situation. In this case, I'd trust the specialist if you can afford it.

Answer 6

Grand pianos are designed to fill large concert halls with crystal clear music, so they laugh at pitiful attempts to silence them...

Obviously switching the piano to an electronic one isn't an an acceptable option to you, as it's something you'd have done without posing this question [price of a good one is same or lower ballpark than your refurbs, you can take it to your next house, and at a pinch even resell].

So, depending on the shape of the walls, are "resilient bars" an option [possibly UK terminology]? They've made a big difference to me where I could hear my baby rustle their blanket in the room next door, as wall was a common cheapo 1970s sheet material consisting of a 2inch "honeycomb" cardboard for rigidity, with about 8mm / 1/4inch of plasterboard on each side.

Every two vertical feet you attach these metal strips over the full length of the wall; they have a metal lip hanging off ther top, about 1/2inch / 1cm off the wall and say 1inch high. Now you attach plasterboard/drywall boards with regular screws to these strips [while keeping good track of the location of these strips you're covering as you go along] with about 1/2inch spacing around. Ideally then you glue a specific rubber membrane onto them, and then you add another layer of plasterboard but staggered versus the first [i.e., if you'd screw through a corner of the top layer and the rubber, you'd theoretically hit dead center of the underlying board]. Around the whole edge you bead an intumescent [i.e., foams/expands in case of fire] but soundproofing mastic.

The simple idea is that this new wall covering thing you've made floats somewhat, freely hanging off these metal strips; they transmit sound (i.e., vibrations) minus the energy that's needed to make them vibrate. Ideally you'd use full 1/2inch /12mm plasterboard not 3/8inch /9mm, and the heavier [UK: pink] fire-rated boards not regular ones. If your staircase allows, use full 4x8ft/122x244cm boards, not half or quarter-size "one man" boards, as not only you'll have less seams to hide but also less 'holes' means less sound-leakage [and the staggering can be less precise].

Easy DIY job if you have the time/inclination [dust!], except for the finishing plaster on top. I didn't get the rubber membrane [so, easy to see markings I made on first layer, about precise bar-locations for second layer], and used regular 9mm thick boards.

All in all the full recipe costs you thickness of the bar-with-lip + rubber (2mm? 2.4mm?) + 1inch of plasterboards (2x 12mm) + finishing plaster (2mm?). I had to do mine in addition to a studwall to hang the bars off (made it 2inch/5cm thick not ideal 4inch, and stuffed with soundproofing rockwool). I could win back three inches by removing the 1970s wall, which would have made an unsleepable mess for weeks then; doing it now would mess up the ceiling, and the door-location in that wall.