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Acoustics and Sound Masking From Cambridge Sound Management

Show 135, Part 1

SVC Podcast – Show Notes – Show 135-1:

In this edition of the SVC Podcast, SVC Contributing Editor Bennett Liles talks with David Sholkovitz, Director of Marketing with Cambridge Sound Management regarding the art and science of sound masking. David details the need for sound masking in today’s office environment and he outlines the components and setup of the company’s QtPro  system. David also discusses sound dampening materials and reducing sound leakage between rooms.

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From Sound & Video Contractor Magazine, this is the SVC Podcast with David Sholkovitz. Show notes for the podcast are available on the web site of Sound & Video Contractor Magazine at

Today’s office environment has changed. The concept of private offices and even cubicles is giving way to open rooms, open ceilings and a shared space that has privacy at a premium. David Sholkovitz of Cambridge Sound Management is going to give us the details on the science and mechanics of sound masking. That’s coming up next on the SVC Podcast.

David, thanks so much for being with us on the SVC Podcast from Cambridge Sound Management and we’re going to be talking about acoustics and sound masking. That’s something we haven’t done many of these podcasts on so that’s going to be a real treat. First, tell us about Cambridge Sound Management. How long has that company been around?

All right. Thanks, Bennett. I appreciate you having me here. I look forward to teaching a little bit about sound masking. So in regards to Cambridge Sound Management, we were actually founded in 1999 in Cambridge Massachusetts. Our founder is an MIT Ph.D. with a pretty deep heritage in acoustics and audio engineering. He actually worked at a pretty highly-regarded acoustical consulting company in the Boston area called BB&N. They did a lot of R&D and research in acoustics and actually are accredited with essentially inventing electronic sound masking many years ago. So kind of that heritage in acoustics coming from our founder and then over the last couple of years – 10 years or so – we’ve really worked a lot on our product development and engineering initiatives to bring to market products that are easy to install in modern facilities. And I think in about 2003 we had our first commercialized sound masking product, so it’s been over 10 years now, really, in the market. [Timestamp: 2:06]

Yeah, and your outfit got in on the ground floor of this technology. I’m not sure that ten years ago anybody would even have known what that was or had ever heard of it. So why is that so important now? What has changed in today’s office environment that has caused sound masking to become such a big topic now?

In the past 10 years the workplace has really changed drastically. There’s about 75 million Americans who identify themselves as office-based knowledge workers who are working in an office or corporate environment. It’s been a big impact on them. From a physical perspective, there’s many changes to the office environment coming along with the open floor plan. Obviously the elimination of the private offices and lowering of cubicles and developing open floor plan spaces that help drive collaboration in communication, that’s been a major trend. Also with furniture and more natural light and use of architectural products like glass and steel for a modern look and feel and also to help with letting more daylight in to help with LEED certification has been a big thing. I mean I think generally the shift into the open office has been great. It’s been good for us and it’s been good for many other office building products that are in the modern office. For employees there’s been some downsides of that, of course, because of course some of their privacy has gone away. So a lot of the sound issues have been created because of the elimination of sound absorption material. So no carpet, there’s less partitions. There’s many open ceilings so the ACT’s – acoustical ceiling tiles – that have played a big role in acoustics by absorbing sound in the office, those are gone in a lot of open ceiling designs, so you’ve got exposed ceilings. You’ve got a lot of sound basically floating around there, so we’ve seen a big uptick in sound masking because of these different trends. It’s pretty affordable technology to go and retrofit into a space instead of having to rebuild it to improve acoustics, which can be very costly. [Timestamp: 4:09]

Yeah, collaboration is a great thing but when you’re trying to concentrate on something I guess it’s good to be able to sort of turn it off and quit collaborating for a few minutes.

Yeah, it’s definitely a balance, I think, of being able to communicate; obviously work with others, right, but also have your focus time or your “me” time to be able to concentrate. I think facility managers in H.R. and management teams try to always find that balance with a comfortable office, but then one that they can create some level of privacy, especially depending on the line of work where some people may need to focus, like a software engineer or R&D developer. [Timestamp: 4:45]

So you’ve got active systems now instead of just passive sound-absorbent materials like tiles and carpet so how does all that work? How does the science of sound masking work, the basics of it?

Yeah, so sound masking is the process of adding to an environment a low-level, unobtrusive sound, and the sound has been engineered at the same level as of human speech frequencies to help protect confidentiality of conversations and to reduce distractions. So we’re basically adding sound to make it feel quieter, so it’s a little bit reversed in how it sounds. We’re actually making it a little louder to make it feel quieter. The key to all of this is reducing the intelligibility of speech, so making it harder to understand what people are saying, that helps make it actually make it a more comfortable environment. So sound masking, it’s not cancelling speech. I think it’s good to make that statement. It’s also not absorbing speech. It’s not blocking sound, but it’s making it harder to hear people at a distance which makes it less distracting. So most office environments with some masking on, a worker would likely hear every word of another employee 40 feet away without a phone. But without sound masking in an office you can hear that person from quite a distance talking. Then once you add the sound masking there you’re introducing some sound into the background. It makes the conversations less intelligible and then therefore less distracting to people. There’s lots of different analogies, but it’s almost like just creating a comfort level by giving a little bit of background sound. It’s like when you’re in Starbucks or the coffee shop. There’s actually a lot of people who like working there because there’s this comfort level with kind of the ambient sound in the background. And similar to an office, some of our clients have offices that are not necessarily always too loud, but also too quiet. Those are some of the worst culprits when it comes to an office because when an office is very, very quiet you can hear everything around you and that’s annoying. [Timestamp: 6:34]

Yeah, nobody wants to talk.

Yeah, so it’s like – and it’s also, then, when it’s an office where a lot of people are talking, that can be distracting. So sound masking helps in both of those situations.

Yes, sort of covering a distracting sound with non-distracting sound.

Yeah, yeah.

And Cambridge has the QtPro system. You have several different models. What are the components of one of these sound masking systems? It’s active so it would have to be composed of several different parts and pieces that have to be centrally controlled.

There are three main components. So while there’s a lot of technology going on, if you break it down into these three components it’s actually a relatively simple system and this kind of simplicity is part of our value proposition for installers. The three main components, you’ve got a control module and also an amplifier. We’ve got different versions, but the control module is the brains of the system. It’s creating the sound- masking sound and it’s got the circuit board and the microprocessor and all the hardware – most of the hardware components. And then you’ve got cables, which is basic CAT-5 cables, which connect the control module to emitters. And then you’ve got emitters. So control module, cables and emitters are the three primary components. We only have one type of emitter, which makes it very easy so there’s one type of emitter for any sort of installation. And then we’ve got different control modules depending on the needs of the customers. And the cables daisy chain the emitters together, so basically it’s a daisy chain system of emitters which are very small – 3-inch emitters. I think we’ve got inch-and-a-half drivers inside of them so they’re very small speakers, essentially, that are spread out in a grid format. So if you look at those three, those are the three main components of a system, so it’s a relatively kind of a simple complex. There’s more complexity of course in the software and how it all works, but as far as installing, those are kind of the three areas. [Timestamp: 8:22]

Now, when you’re going to install one of these you don’t just go in and start hooking things up. You have to sort of analyze the environment. Are there specific measurements that you have to make to determine the settings on the system?

It depends on the complexity of the client site that you’re in. It’s a pretty much plug-and-play system so there’s no commissioning or tuning that needs to be done. As far as measurements, yes there are measurements out there. There’s the privacy index, there’s the SPP, which is speech privacy potential. That’s how you measure speech safety in an enclosed office, like a conference room. So there’s generally that you want to look at those things when you’re in a space. Generally you want to just understand the speech intelligibility, so how does the environment react to noise and to sound? You can get pretty technical if you want to do a deep dive into a space, but a lot of it is just understanding, once the system is deployed, getting the right dB level; making sure the zones are set up correctly in the environment. So yeah, there’s different things that you can do. There’s a lot of standard kind of acoustical measurements out there that are pretty well-known and agreed to by the community. [Timestamp: 9:31]

And of course these are active systems and we were talking earlier about how a lot of the absorbent materials have been phased out of modern offices. What are those typically? Carpets, drapes, acoustic tiles and things like that with just sound-absorbent material?

Yeah, that’s correct. Yeah, acoustical ceiling tiles are the big one because the square footage that you’ve got coverage of that, the ceiling is everywhere. So those are the big one to absorb sound, so as soon as you blow those out and you’ve got an exposed ceiling, you’ve lost a lot of sound absorption space, or coverage I guess. Carpet, as you mentioned, is definitely a big one. Again, that’s everywhere and if it’s a fully-carpeted building that used to absorb a lot of sound. Now you’re seeing offices that have either hardwood floor or they’re doing concrete floors completely or tiles or whatever, or selective carpet usage. Cubicles, the fabric on cubicles is designed for sound absorption. And then you have companies that have gotten pretty creative with drapes and panels and even plants that were designed to absorb sound, you know, artificial plants and some other cool things. There’s some pretty funny products out there that absorb sound, that are also pretty quirky. [Timestamp: 10:42]

And with all of the experience that your outfit has had in acoustics and sound masking what would you say is the most difficult or challenging part of installing a good sound-masking system?

You need to make sure that you’ve set up the zones correctly in an environment, so proper zoning, I think, would probably be the most challenging thing. Some masking systems must be flexible enough to accommodate complex architectural spaces, using a ceiling-height furnishing type would come into play. You’d probably want different zones to get a consistent sound field created. So there’s some tweaking you need to do in the zones. By dividing a system into zones, though, it does make it easy because you can kind of break it into smaller pieces. So if you’ve going into an office that’s got a lobby with 20-foot ceilings, you can do a zone there that just covers the lobby area, do another zone that maybe comes through the hallway, and then another zone in an open office and another zone for private offices. So by zoning, breaking a space into its different variables, for an average office size – I don’t know, if you’re doing 5,000-8,000 square feet or something like that – you just want to make sure you get the zoning right. I would probably say that’s the most challenging. We do designs. We have a design team that can help do that here for you, we just need the acoustical ceiling plan layout so we can make a design, put emitters in the right place. I think once the ideal sound-masking kind of frequency level is established, the other thing is just amplifying it to the right level, and that’s just a sound level check. It takes a little bit of engagement to get that right, but zoning, I would say, is probably the trickiest part. [Timestamp: 12:16]

I guess that could be complicated as far as the zones if you’ve got some sound leakage between the rooms.

You know you always want to have the sound-masking system laid out where the unintentional listener is, right? And when it comes to between rooms, if you’re doing a full deployment we’re going to have an emitter about once every 100 square feet, including that both in rooms and in open office areas so we cover the whole space. By covering the whole space you ensure that you’re helping to mask sound in all the right areas. You may have the zone level a little bit lower in a private office because you don’t need it as loud because you’ve got some natural sound blocking going on with the glass and the walls, so you have a little lower level in there. But it definitely helps cover the leakage. [Timestamp: 12:57]

Well, I know there are all kinds of tricks to the trade and there’s no substitute for experience in doing this and it’s been great to get the quick two-dollar tour on the science of sound masking. In Part 2 we’ll get into the privacy index, direct field systems and thing like that. David Sholkovitz from Cambridge Sound Management, thanks for being here with us David.

Thanks, Bennett. I appreciate it.

Thank you for being here with us for the SVC Podcast with David Sholkovitz. Show notes are available on the website of Sound & Video Contractor Magazine at Join us For Part 2 when David gets into the ABCs of sound masking and clarifies some other terminology for us. That’s on the next SVC Podcast.

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