Acoustics and Sound Masking: Planning Noise Control

July 12, 2005

The acoustical properties that give a space its signature sound - ranging from musical to hushed, well-controlled to clamorous - are an essential ingredient in today’s leading architectural designs.

“Acoustics and architecture should always be fully integrated - not layered or discrete,” says Mark Holden, chairman of Jaffe Holden Acoustics (, an architectural firm whose work has included the acoustic designs for such clients as Zankel Hall in New York City’s Carnegie Hall and the Concert Hall in Washington, D.C.’s John F. Kennedy Center for the Performing Arts. “Each architectural site has unique acoustical needs, as sites are different and clients’ mix of requirements, budgets, and schedules shift from project to project.”

While no two projects are ever exactly the same, Holden says that certain constants in acoustical design are widely recognized. “Concert halls need live, reverberant sound that surrounds you - without amplification,” he says, “while theater needs tightly controlled sound that is crystal clear in every seat and may well be amplified. Museums often want the message to be learned and retained, and audio systems must be tightly focused and very clear, but not too loud to overpower neighboring exhibits.”

To Joakim Hannerz, a principal in the broad-based architectural firm HaHa + Company (, the strong connection between architectural and acoustical design is often overlooked. “The relationship with acoustics is probably one of the more subtle and least-thought-of aspects of architecture,” he states. “It’s something most people don’t take into consideration - or at best becomes an afterthought when there’s a problem. I think acoustics is, if it’s done right, a sublime luxury to some degree.”

John Storyk disagrees. A principal with Walters-Storyk Design Group ( and a recently founded firm known as Intelligent Acoustics (, Storyk insists that good sonic properties aren’t a luxury at all. “We believe very strongly that acoustics issues need to be addressed from the early programming stages of a project,” he says. Storyk’s credits include many of the world’s top recording studios, as well as broadcast, corporate, educational, residential installations, and more. “Obviously there are spaces in a building that are not acoustically sensitive, but more times than not, there are early planning issues that involve acoustic criteria. Establishing these criteria, both for sound isolation as well as internal acoustics, is important. In fact, there are often projects where we as acousticians are hired before the architect and other design professionals.”

Storyk says that the tools available for designing and predicting the acoustic properties of a space have become more accessible and compatible with desktop computers. “This has made our job more fun,” he admits, “but continues to create higher expectations from clients.”

Acoustics, defined as the scientific study of sound generation, transmission, and reception, boils down to a short list of main components when discussed in conjunction with architecture.

“There are three main factors that determine the acoustical properties of a space,” Holden says. “First is the volume, i.e. air contained in the space: The taller and the more square footage, the higher the volume. The second factor is the surface materials or furniture in the space. Lastly, the noise of systems, traffic, hums, and buzzes in the space.

“The rule of thumb is that as the volume of the space increases, additional sound-absorbing surfaces need to be added to control the buildup of sound. For closed offices, either the floor or ceiling should be treated; in open offices, treat both; in performance spaces like movie theatres, treat the walls as well! For live theatre, music, or concerts, call an acoustician.”

While these qualities can be planned on the drawing board, the real world can often introduce obstacles to well-defined acoustics. “The biggest challenge is usually getting the program to synch up with ideal acoustic conditions,” Storyk reveals. “For instance, imagine we have a room that we know has to sound good for speech. We should dampen 50 percent of the surfaces, but the program doesn’t allow that because the client also wants a wall of windows to look at the Rocky Mountains. So now we have a conflict. The acoustician’s job is to assist the design team in solving this balance.”

Hannerz describes the challenges this way: “Materials that are durable enough for public spaces tend to be hard surfaces, and that means you have very little space left over to cover with sound-absorbent surfaces. The second challenge is really one of cost. Some acoustical products are very good, but they don’t come free.”

Despite such challenges, new tools can help ensure the design of a superior sonic environment. “On the software end, measurement and predicting tools have really sprung up,” says Storyk. “Auralization has been an increasingly popular tool in the field. This gives you the ability to ‘listen’ to a room from a type of CAD drawing that has the attributes of physical materials attached to the surfaces. An impulse response, which is the acoustic signature of the room, is created in advance instead of being measured after construction. As a result, you can listen to what a room sounds like before you build it.”

Once the space actually exists, Holden advises making the most of what materials are selected. “I strive for acoustic treatments that perform a number of functions - three at least - and are fully part of the building,” he says. “I don’t believe in adding ‘acousticals’ to surfaces. A sound reflector can serve as a theatrical lighting position, a house light location, a rigging platform, air diffuser, and a beautiful floating element in the hall.”

Holden adds that the most familiar materials, acoustic panels and tile, are a tiny percentage of what’s available. But like Hannerz, Holden cautions that superior sound has a price. “Cost must be kept in mind,” he admits. “Acoustic materials are always more expensive than cheap drywall and raw concrete. Why? Because they have special cores that turn sound into heat in very specific ways, and they often need covering with fabrics, perforated metals, or wood grilles.”

Hannerz says that “a huge burst of new acoustic materials” has emerged in the last 10 years that is revolutionizing acoustic treatments. “One of the materials I’ve been really impressed by is BASWA®phon, which is an absorptive, continuous surface - instead of grid work - that can blend in on walls and ceilings,” he says. “Both Woodtrends and Formglas fall under the category of materials that are perforated, which have a hard look but let sound pass through and deaden it. “Woodtrends is a wood material with a perforated surface, but it’s beautiful and enhances the space rather than being something you have to have there solely for the acoustic properties. Formglas is a cast plaster or cast metal and can be sculpted in any number of shapes.”

One material that Hannerz says he has not yet used but finds intriguing is the stretch membrane ceiling, “where the membrane is acoustically transparent, and you can have any other sound-absorptive material above it.”

Another technique for controlling sound is “masking,” a term that describes the intentional application of ambient noise in certain situations.

“More and more companies are moving to an open-office environment as opposed to individual offices,” notes Jim Scheer, president of the A/V firm Innovative Technology Group ( “You have multiple workstations with shortened walls separating people. With sound masking, if someone is having a conversation right next to you, you might still hear it, but you won’t be able to hear exactly what’s being said. Lencore manufacturers a great product that has master/slave capabilities, independent volume per zone, and a built-in amplifier. Armstrong creates a very good ceiling tile-based sound masking system, and Atlas Sound makes a system similar to Lencore’s.”

As architecture and design evolve, Hannerz points out that a big part of acoustics is also about keeping abreast not only of new ways to absorb and diffuse sound, but of the new sound sources that could be complicating the picture. Even sounds beyond the range of human hearing should be taken into account, he believes. “The amount of electronics that are generating noise at many, many different frequency layers are cumulative,” Hannerz says. “I think it will be a great improvement for all projects to be much more aware of all these acoustical factors.”

According to Scheer, the rapid evolution of acoustic aids and options for architects can be expected to continue unabated. “The biggest breakthrough we’ll see is the equipment will get better at managing multiple inputs and different sources,” he predicts. “Manufacturers of acoustical treatments will be able to blend their treatments into the environments.”

But often,the experts point out, acoustical excellence can come down to little more than common sense.

“Sometimes the seemingly most obvious solutions elude everyone except the trained eye or ear,” Storyk says. “If you want to make sure a conference room will be quiet, don’t put it next to a noisy space!”

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