Active Noise Cancellation for Conference Room

[dorimardr]

Hi!

I am currently trying to find a good Active Noise Cancellation System for a conference room that we are currently designing. The room is 26' l x 14'-8" w x 9' h. One long wall and one short wall are made out of STC 55 gypsum board and have acoustic wall panels; the other short wall is made out of concrete; and the other long wall (26' l x 8' h) is made out of 1/4" tempered glass with silicone butt joints. We have gypsum board and acoustic ceiling panels in the ceiling.

Previously, we considered using a 6" w insulating glass with a 4" air chamber to create both temperature and sound insulation. The problem with this glass is that it needs a metal structure with mullions every 4', and we really wanted a seamless look. In terms of sound, we wanted a insulation of STC 51, but since we changed to the tempered glass, it is probably bellow STC 30. So, not good...

My client does not want the insulating glass, so he told me about a system or device used to cancel noise. My biggest concern is privacy: sound getting in and sound getting out. I don't know which system will work best for this project. Do you know of any company? Anything that could guide me through this? Any advice? I appreciate any help!

Thanks!

 

[axemaster]

Hi, I have designed a few sound canceling devices for my own (non-commercial) use over the past 2 years. I am trying to understand what you're doing here. Are you trying to stop sound in both directions or just one? And based on what I understand from the STC51 rating, you think you need a 20dB improvement over your current STC30 rating?

Now, I'm certainly not an expert in this sort of thing, but my snap judgement is that shielding a room of that size using active cancellation is probably impossible. By "impossible" I mean extremely expensive, prone to failure, a tremendous number of cancellation devices required, etc. You will probably need hundreds, if not thousands of canceling devices to get decent coverage. Maybe some clever person at a company has figured out an ingenious workaround, but I kind of doubt it.

Given that, you'd probably be better off just using standard passive sound stopping materials. Actually I'm wondering why you have a problem at all - most of the conference rooms here at MIT have heavy glass doors and walls and don't seem to leak much sound.

Sorry if that's not much help, I'm just giving a very general answer to a very general question.

EDIT: If you want to talk to a real expert, I would suggest contacting someone who works at a company that makes noise-cancelling headphones, like Bose.

 

[dorimardr]

Hi,

Thank you so much for replying. I will answer your questions bellow:

1. I thought about blocking sound on both directions, but after reading your answer I think that blocking sound on one direction will be more viable. I understand that I can use acoustic materials inside to prevent sound from leaking, so that will do.

2. STC 30 is not a terrible rating, but we really wanted to get to STC 55, to comply with conference room STC suggestions. This STC is not required by any agency or code, so we can be flexible.

3. The issue here is that the project is not built yet, it's still in its design phase, so we have no clue as to what level this glass partition is performing in terms of sound insulation. With a tempered glass of 1/4" thickness, I am worried that it will be too thin and sound will leak easily. But, on the other hand, using too many devices does not make any sense. I completely understand what you are saying, and I agree with you.

4. I will definitely talk to the people at BOSE. Thanks for that suggestion!

I really appreciate your answer. Thanks!