Acoustics and Sound Management from Cambridge Sound

Show 135, Part 2
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SVC Podcast – Show Notes – Show 135-2:

In this edition of the SVC Podcast, SVC Contributing Editor Bennett Liles continues his talk with David Sholkovitz, Director of Marketing with Cambridge Sound Management regarding the art and science of sound masking. David details some of the more challenging QtPro sound masking system installations and he takes us into the ABCs of sound masking; Absorb, Block and Cover. He also explains the differences between “direct field” and “in-plenum” masking system types.

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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

Despite all the exact science behind acoustics and sound masking, it comes down to experience when installing a system to limit noise AND increase privacy. David Sholkovitz of Cambridge Sound Management is back to wrap up his talk about the science and mechanics of sound masking. That’s coming up right now on the SVC Podcast.

David, thanks for being back with us for Part 2 on the SVC Podcast from Cambridge Sound Management, sound masking system experts. We talked last time about the basic science of it and science sets the stage but then actual field experience comes into play. Tell us about some of your more challenging projects with the QtPro sound masking system. That’s the one you handle.

Yeah, that’s correct. Yeah, you always have some challenges when you work in all sorts of vertical markets. We will jump from doing a hospital to a university to corporate offices, call centers, things in the U.S. and in 30 different countries. So you run into all sorts of architectural designs that make sound masking deployments challenging. I think one that jumps up to me is actually in Stanford University. They’ve got – well, there’s two different things. One is there’s a very complicated library that we did there and then there’s another situation, and I believe it’s at Stanford, which is a classroom environment. So the university wanted to have the ability for a teacher to give a lecture in a big classroom size, kind of stadium seating like normal – but they also used that classroom to do breakout sessions so the students would then take a task and work together in teams. And they didn’t want the students to have to get up and leave the room to go have privacy in their different breakout sessions, they wanted to do it in the room. So the installation company and the AV company and I think some of their in-house engineers used our products in a real cool way, which was basically when the teacher is talking there’s no sound masking on because you want to hear the teacher speak, right, very clearly. And then the teacher would have the students break out into their breakout sessions in the room and they would slowly ramp on the sound masking actually in the classroom and that would allow the teams to break out in their sessions, so their business plans or whatever they were working on together with sound masking on to protect them from hearing each other and to reduce distractions. And then when the professor was ready to speak again, he or she will turn the sound masking – ramp that down and then comes back to the non-sound masking environment where you can hear everything. They thought it was kind of a cool way of deploying it into their control systems. We have an API, so I think they’re using an AMX or Crestron system. It can all be controlled through the system. But that’s kind of cool how they’re turning it on and off. That’s very unusual. Usually sound masking is something that’s on all the time in an office. But in this situation it was kind of cool how they use it to cover up speech when the students were in breakout sessions and then turn it off when the professor had to speak and address the class. [Timestamp: 3:19]

You know, that’s something I didn’t consider before but turning it on and off could create a whole different environment especially if you do it in a subtle way. And if it works right, the people there just hear what they need to hear but they probably don’t give it a second thought.

That’s an unusual circumstance. Like you said, usually you don’t want people to know it’s there so it’s always on in the background in an open office or a call center or wherever you have it. In this case it was kind of interesting because it does come on and off with the control system depending on what the teacher is doing. And most of our more challenging ones are just doing drop ceilings, or sorry, open ceilings where we’re, you know, a lot of renovated lofts and locations that are kind of half glass/half brick, doing a lot if refurb buildings where we’ve just got to do a lot of mounting. We’ll have rods that actually bring the emitters down. Our product’s really easy, or it’s good for open ceilings because it’s coming straight down into the space; it’s not a plenum solution so it’s easy to mount the emitters. We have black ones so a lot of – we do a lot of black ceilings, which is kind of a trend of having an open ceiling that’s painted black. But yeah, there’s always a lot of challenges out there. [Timestamp: 4:28]

Yeah, you can be very subtle with one of these systems. So give me the basics on what this does. I think on your site there’s the ABCs of sound management. Absorb, block and cover.

Yeah. These are really the fundamentals of not necessarily sound masking, but the fundamentals of architectural acoustics and things to consider in an acoustical way about building a space. So we have A, B and C – absorb, block and cover. Absorb is the principal of adding sound absorption material into a space to absorb sound. So this is adding carpet, ceiling tiles, drapes, furniture, cubicles; those artificial materials that are set up to absorb the sound in an area. And then of course you’ve got block, the B, which is building walls, building up cubes, building private offices. You’re literally blocking sound. You’re putting something up there that’s supposed to block it and be more permanent. And then there’s C, which is cover, which is where sound masking comes into play. That’s about creating an ambient background sound to help cover up sound. So together the ABCs of acoustics help form kind of a fundamental baseline for how an architect or an AV consultant or audio consultant can go into a space and think about the different things to tackle to make a comfortable acoustical environment. And it’s important not just to focus on one or the other. I mean we often tell customers that it’s not just sound masking. If your space is having other issues you may want to consider adding in some sound absorption material as well along with some sound masking from the cover side to make sure that they’re fully addressing the acoustical challenges of a space. And this applies both for private offices, enclosed areas, and open offices as well. [Timestamp: 6:12]

And one of the things that you mentioned before, I think it was in Part 1, is the Privacy Index. What exactly is the Privacy Index?

Measuring the speech privacy is very essential for organizations to try to achieve a level of confidentiality and privacy in their offices. The Privacy Index is an industry-wide term of measurement that’s used by acoustical technicians across the country. It’s been widely supported by different associations and groups. I guess generally when we have the system – so say we install a sound masking system, we generally want to achieve a normal speech privacy index of 80 or greater. So it’s from zero – I think it’s 0 to 100. It’s not on an even curve. So 0 is absolutely no privacy, 50 is still pretty much absolutely no privacy, and then starting at 60 and above is where you start to see measurements that would actually create some privacy for people in the space. So I guess with sound masking we’re trying to shoot for a privacy index of 80 percent or greater, which is an open plan area. At 80 percent you’re starting to have some – you’re starting to have speech be unintelligible; 85 is a really good goal to have in an open office space. And then if you’re going into a closed office, a private office, you want to hit the 90-95 percent on the privacy index level to have full, very confidential privacy in an office. So to sum it up it’s a scale of privacy for individuals that’s used by designers and acoustical consultants to measure the comfort level and the privacy level in the space. To boost sound masking you want to get in the 80-85 area for an open office space to make it comfortable, but you’re not hearing people’s conversations at a certain distance away from you. [Timestamp: 7:59]

Okay. And I know that can be critical in establishing the right environment in a conference room or in a busy office with a lot going on all the time. I’ve also heard of the direct-field system versus the in-plenum type.

Those are essentially the two types of sound masking systems that are on the market. So our products are direct-field and direct-field means that the sound masking speaker is facing down into the office environment so the only thing between the speaker and people in the environment is air itself. And in-plenum speakers tend to be a little bit wider, a little bit bigger, and they are facing up and then they fire the sound up and then it reverberates off the ceiling and then bounces back down through the ceiling into the space below it. Most of the traditional systems are all in-plenum, so there’s speakers that get hung on wire from the ceiling and fire the sound up and then bounce that down. And those were used for many years. We actually patented and developed direct-field sound masking so we have smaller speakers. There’s more of them in and environment because they’re smaller, but they go into the ceiling facing down or mounted in an open ceiling and then they send the sound masking directly down into the space. Those are kind of the two different systems that are out there and you really – I would just urge installers and also end users to think about what works best for them in their environment. The direct-field system we feel strongly it’s very effective in being able to eliminate hot and cold spots and make it easier to install because it’s just a tiny speaker that can be mounted anywhere or put into a ceiling tile and doesn’t need to be mounted in the plenum, but generally we feel like it’s got a higher quality level when you’re introducing that sound right into the space. It’s just more effective. So those are kind of the two different systems that can be used. [Timestamp: 9:48]

So when people come to you and they’re interested in a sound masking system, I guess they’ve usually done a little bit of research. So what types of places can benefit the most from a good sound masking system? We mentioned classrooms and boardrooms.

Classrooms, boardrooms. The most common application are open floor plan offices. We have a lot of people in one space and generally offices that have no background sound or they’re very quiet are good candidates for that. And then also those offices that are – where you have like a sales center, if you have a call center where there’s a lot of people chatting and talking and it’s a whole lot of human speech going on, sound masking also can help in that environment and reduce distractions. But yeah, private offices, call centers, engineering labs are big. From a vertical market we do a lot in healthcare, hallways, nursing centers, waiting rooms, patient rooms, doctors’ offices. Those types of areas are good because you need to protect conversations between doctors and patients and patients and staff and there’s HIPAA regulations and other things that help regulate healthcare facilities to make sure those conversations stay private, so healthcare is big. Hospitality, we’re doing hotels here and there and then we have the tech sector in general is big. These companies are moving towards office spaces and they’ve got a lot of engineering and R&D centers where we cover it up. And then government is a big vertical for us as well. So the applications of office/conference room/private room – every vertical market has those spaces so there tends to be   very wide variety of uses of sound masking throughout – in almost every industry, so that’s great. [Timestamp: 11:23]

Why do you use a multi-channel sound masking system? Is that so that you can create different zones?

It’s not for different zones. Our systems are set up so we can have up to six zones on one amplifier. That’s separate from multi-channel. So why do we use multi-channel? Well, when identical signals reproduce through two loudspeakers placed a distance apart, comb filtering affect is basically heard by the listener as they move through a space. So if you didn’t have a multi-channel distribution you could actually hear the difference in sound between speakers. Absolutely not what we want to do. So this audible difference, if you had two speakers using the same channel you could localize it and you could tell where the speakers are in the ceiling, but more importantly you would notice it more. The comb filtering is technically due to the fact that as some frequency is emitted the audio signals are basically summing each other and at other frequencies the audio signals between the two sound sources are cancelling, which would reduce it. So by using four non-coherent noise sources or channels, we’re able to lay out the masking system to minimize the effects of comb filtering by basically ensuring that no two like noise sources are playing through adjacent emitters. So you know you’re never going to hit two of the same noise sources in the same area close to each other, which at the end of the day makes it much more comfortable and a much more effective sound masking system because you can’t localize it and you can’t hear the difference between the speakers so it gives it a very even distribution. [Timestamp: 12:54]

Okay. And on power consideration, I guess these things don’t use a whole lot of power any more than a home stereo system would or anything, but how quick are they to come back up if, say, you have a power outage?

Yeah, so our typical control module will take about 20 seconds to reboot after a power outage for our Qt100, 300 and 600. It’s about 20 seconds, so it’s not long – not a long reboot period. And then on the power, you’re correct. They draw very little power. Our Qt100 devices powers only seven watts – draws at seven watts. Our biggest control module only draws 27 watts of power and that’s to cover 72,000 square feet on 27 watts. So it’s like an exit sign as far as the amount of power that’s actually drawing off the system. [Timestamp: 13:43]

Yeah, looks like a real bargain in terms of the effect versus the power that it uses. So what’s happening at Cambridge Sound Management? Have you got any interesting projects in the works coming along?

We just launched a project at Infocomm for conference rooms, so the Qt Conference Room Addition. This is our first product that was built for targeted sound masking. The control module and the signs go in a conference room which will alert the participants that their meeting is being protected and then the speakers actually go outside of the conference room, outside of the glass walls or other walls if it’s drywall or whatever. So this is our first targeted application for conference room AV and we hope the AV installers who are doing a lot of conference rooms can help create awareness with end users that there is a privacy issue and that there’s a technical solution to solve that. We call this the privacy solution for conference rooms. So this has been a big focus for us in the second quarter and third quarter. We do a lot of retrofits and there have been lots of new construction projects. When it comes to new design those projects typically take a little bit longer and we’ve worked with various architects on those. I can think of a lot of pretty interesting companies that I probably shouldn’t name, but different tech companies and financial services companies doing some pretty big installs. I think it’s good to see the market rebound a little bit, especially in commercial real estate and commercial development. We’re seeing a rebound of the economy and things are getting better so people are investing in their offices as well. And then yeah, I guess we’re seeing more integration with control systems of sound masking so it’s kind of being a more common staple within especially conference rooms and high-end conference rooms that sound masking is kind of a core component of the AV buildout. So there’s always interesting things coming on so it’s fun because we do a lot of the designs for our installation partners so we see a lot of designs and help lay it all out. And then of course go there and commission, if necessary, with our partners to make sure everything is done according to plan. So it’s always busy. [Timestamp: 15:43]

Yeah, it sounds like it. It’s an incredibly interesting line of work and the science behind it is complex and just amazing. The systems can create a real effect and a whole new ambient environment. Thanks very much for taking us through this and kind of getting us up to speed in sound masking technology. It’s David Sholkovitz from Cambridge Sound Management. Come see us again sometime.

All right. Thanks a lot, Bennett. I appreciate the time today.

Thank you for being here with us for the SVC Podcast with David Sholkovitz. Show notes are available on the web site of Sound & Video Contractor Magazine at Be back here with us for the next SVC Podcast.