French (glass) doors, sound proofing

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Hello,

A couple of psychologists I know are taking a 2 year commercial lease for their work. I'm helping with setup, and have been asked how to stop sound (conversations) leaking between the rooms.

There are french doors in the wall between the two consulting rooms, and I assume that's how most sound will leak through.

They shouldn't be expecting miracles - I've explained that sound conditioning is easy, sound proofing is hard. Also, what I can do is quite constrained:

- nothing irreversible / marring / ugly.
- I should probably leave the french doors capable of opening (this may be a legal requirement / fire safety issue).

I was considering:

(a) sealing the airgaps around the doors
(b) deadening the glass
(c) hanging a curtain in front - mostly to hide (a) and (b)

Sealing the airgaps seems like a job for weatherstrip foam.

Deadening the glass - tips? I was thinking of using double sided tape to attach a layer of something-or-other.

Is there anything obvious I'm missing?
 
Replace the french doors with something denser that isn't glass. The thicker the better. If you can get pictures someone may be able to give more specific help.

For how limited you are you're on the right track. If you do hang curtains you want them as thick/dense as possible to help.

To stop conversations between rooms you also need to consider air ducts as a possible transfer space. Another thing that you can do which won't "stop" the conversation transmission but may mask it is to add white noise generators. We have those at my work to cover the noise and it's a noticeable difference between when they're running and when they aren't.

If you can't replace the door then attaching MLV and then going across the entire doorway with the densest curtains I could find would be my approach. Don't expect miracles obviously which you seem aware of.

One other thing, there's a gap at the bottom of the door probably. Depending on the HVAC setup in the building this may be required and expected for proper air flow. You might not be able to block that without needing to maybe add window fans or something. I'm speaking from a US building standpoint here but the possibility stands elsewhere.
 
diyAudio Member
Joined 2007
Is that acoustic pinboard similar too or the same as the old perforated Caneite from CSR?
Interested in how you did the curtains as I have a huge window that needs better treatment. I have lots of pre-quilted Thinsulate to use as an absorber but finding heavy and affordable curtain fabric is hard
 
Is that acoustic pinboard similar too or the same as the old perforated Caneite from CSR?

No, this stuff:

Gunnersen 1200 x 2400 x 9mm Acoustic Pinboard | Bunnings Warehouse

(if the link breaks: a grey synthetic panel that's halfway between felt and dense sponge).

It weighs very little. You can cut and screw it almost like wood.

Interested in how you did the curtains

Nothing special. It was a rush job, not something to emulate :)

Anything more would have been overkill, really. The dividing wall between the two rooms is also pretty light and acoustically leaky.

I have a huge window that needs better treatment. I have lots of pre-quilted Thinsulate to use as an absorber but finding heavy and affordable curtain fabric is hard

Maybe a multi-layer approach would win?

That is: use something ugly (old blankets?) as the "heavy" part, and hide it with a face layer of normal fabric.

Also, as I understand it:

a) a light fabric can be made more effective by using more fabric on the same length of rod (so it is more deeply pleated / corrugated).

b) the lowest effective frequency is determined largely by how far out from the glass it hangs / extends.
 
diyAudio Member
Joined 2007
OK I am familiar with the polyester board.
WAF means no old woollen blankets allowed in the loungeroom but that is what I used in the other house. Hot washed with washing soda to shrink and felt them too.
Current stand-off is 70mm I'll see if SWMBO will allow a bit more so we can have deeper pleats. The Boss wants new curtains as soon as the renovations are finished. Still trying to talk her into deep pelmets as part of the window treatment
 
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