in December 2006
NCAA Scores AV Alley Oop
By R. David Read
Long simmering problems are resolved, finally.
|The view of NCAA's headquarters building shows the fourth level
vaulted ceiling building in the background.
The National Collegiate Athletic Association (NCAA) recently renovated a major portion of its relatively new four-story, 1.5-million-square-foot headquarters building in downtown Indianapolis IN. The original structure, designed by the eminent Princeton NJ architectural firm of Michael Graves & Associates, is an architecturally stunning building that has a top floor incorporating 30 25-foot-tall, 34-foot-wide, barrel-vaulted ceiling segments. The barrel vaults run laterally for the full length of the ceiling line. Unfortunately, the pleasing aesthetics of the ceiling design came with some undesired acoustical consequences, which were further compounded when attendant acoustical treatment was “value-engineered” out of the project.
As the building was occupied, it became apparent that its function as a working office space was being compromised seriously. In an ill-advised attempt to correct what was essentially an acoustical problem, an improperly executed electro-acoustic “sound-masking system” was installed. This bandage approach did little more than compound the existing problems. The imposed sound masking audio was some 10-15dB above recommended levels for these types of systems and an inverted equalization curve was exceedingly discomforting to the occupants.
According to reports from the consultants, the owners were so frustrated that plans were afoot to cap off the barrel-vaulted open office areas with a simple, suspended acoustical tile ceiling, a process that would have cost in excess of $1 million and would have meant the architecturally stunning environment would have been utterly destroyed.
Acoustical Problems Prevailed
In the open office space area where workstation cubicles are located below the vaults, occupants of these spaces could hear audio interferences distinctly at even whispering levels, even though the offending “noise” was being generated some 100 feet away from them. As noted, the planned acoustical treatment for the ceilings had been eliminated; the result was a smooth, highly reflective, curved expanse of untreated gypsum board. This gave rise to a “whispering wall” effect, whereby very intelligible energy could travel around and across the vaults in the concave ceiling. This is somewhat analogous to how a rock thrown across a lake surface will “skip” along the water while maintaining energy and direction.
The interference was of sufficient magnitude that workers complained that echoes and acoustical reflections were being coupled into telephone instruments to the extent that sounds from adjacent workstations were discernible clearly even to listeners on the other end of phone conversations. In a vain attempt to overcome these effects, the masking generator’s output volume was increased dramatically, thus adding even more to what already was an acoustical catastrophe.
Given these types of problems, confidentiality was virtually non-existent between certain office spaces, and not a problem between others. Geometric reflections were very specific in some areas, and hardly noticeable in others.
Furthermore, not all spaces were uniform architecturally. In some areas, a more traditional lay-in ceiling tile construction was employed. These spaces had their own specific acoustical deficiencies, although not to the same degree as those being experienced in the vaulted area. Despite the non-uniformity of the spaces, only one masking generator with one masking equalization curve was provided.
Defining the Problem
Those who are familiar with acoustics and electro-acoustic systems have seen this unfortunate scenario played out all too often. The value of a dollar is well understood by economists, accountants and building committees, but the projected subjective elements of adverse acoustics are not as readily discernible. Consequently, when budgets get tight, acoustical treatment frequently is an early fatality.
However, it is also an economic axiom that remedial architectural corrective measures often come with a high degree of disruption to the workplace and a hefty price tag. Clearly, a building in which employees have difficulty working effectively has a direct effect on productivity. NCAA management was acutely aware that there was a significant problem, and began searching for solutions.
In some situations, a “sound-masking system” (also known as “speech privacy system” or “task concentration system”) can be used to offset some detrimental workstation interferences and improve productivity. But in situations as described here, layering a sound-masking system onto a severely deficient acoustical space can be a destructive influence that merely serves to compound the problem. On the other hand, as mentioned, remedial architectural processes can be long, drawn out affairs that are both disruptive and costly. Given the circumstances, it is understandable that the client initially chose to have a relatively simple sound-masking system installed in hopes that the detrimental conditions could be alleviated.
The original masking system consisted of a single-channel, “one size fits all” design. Consequently, the generated masking sound signal was piped into all spaces simultaneously, even though the spaces were quite dissimilar in acoustic properties. Of course, being a single-channel system, there were no allowances for tailoring the spectrum of the sound as it was delivered to the varying acoustical properties of the dissimilar environments.
The signal delivered was, at best, a severely compromised spectrum that was not particularly suitable for any one of the treated spaces.
A basic tenet for sound masking or speech privacy systems is the need to maintain a signal that is not intrusive to the occupants and one in which the occupants basically are unaware of the presence of such a system. In this situation, even though the system was DSP-based, it was not secured from being adjusted arbitrarily by well-meaning, but non-technical, personnel.
To alleviate a condition whereby masking sound bled into a recording/production suite, an external hard-wired switch was installed that allowed the building engineering staff to, on demand, simply turn off the system completely. This was not exactly a discreet approach that went unnoticed by the building occupants.
As might be expected, when a 55dBA noise source is turned off and on abruptly, complaints flooded in that the system was either too loud or that it was too hot because, apparently, the air conditioning had shut down.
Must Be Unobtrusive
|Cross-section of the renovated vaulted building.
Another principle in the design of an effective sound-masking system is that, to be unobtrusive, the occupants must not be able to localize or discern the source of the signal. This principle was grossly violated when the original system was, yet again, re-wired to permit it to function as a paging and background music distribution system. An already ailing system thus was altered, making it even more dysfunctional and ineffective.
Further compounding the problem, during the various modifications, many of the loudspeakers were mis-aimed or improperly tapped; hence, the resulting diffusion was poor. In some instances, loudspeakers had been aimed into the vaults, resulting in coverage variations that were lobed and amplified. Variations were so severe that a 20dB increase in masking levels could be observed by merely walking down the aisle for a few feet, followed by a 30dB drop after the next step or two.
Proposing a Solution
At this point, the owners had reached a frustration level that mandated a thorough acoustical evaluation and preparation of a conclusive proposal aimed at actually solving the problem. The architectural firm of Carson Design Associates, Inc., in concert with the acoustical and AV-design/consulting firm of Wright Consulting Associates, Inc., was engaged to study the problem and make recommendations. Both the architect’s office and the acoustical consultant are Indianapolis-based concerns, and both had previous experience with NCAA projects and other corporate clients with similar acoustical problems. NCAA made it clear that it wanted an integrated solution and not just an electronic “black box” wired in.
A battery of on-site tests quickly confirmed that the deficiencies were, alas, all too prevalent. As consultant, David Wright commented, “Because masking is meant to increase privacy and improve task concentration, it was realized that this building, with its several hundred occupants, was far from getting any benefit as originally intended. It became obvious that no masking system would ever work, until the acoustic issues were addressed.”
Wright Consulting frequently uses industry standard EASE 4.1/Aural-ization/AURA modeling. However, in the case at hand, the company realized that it required even more help calculating high incident energy geometric reflections from concave surfaces. Consequently, software-based “ripple tank” studies were employed. These studies clearly revealed that simple noise masking procedures would not prove satisfactory nor, in the opinion of the consultants, would simply adding absorption or “fuzzy” panels to the room be effective in alleviating the geometric reflections and echoes inherent to the untreated vaulted architecture.
It became obvious that some combination of physical acoustical correction and an adaptive electro-acoustic system would have to be designed to meet the client’s expectations. The question then became how to accomplish the aims in the most cost-effective and least time-consuming manner.
The consultants’ recommendations outlined a rather innovative solution incorporating varying acoustical treatments coupled with a materially revamped masking-sound system. Based on their testing and modeling, they expressed confidence that their proposed system would be cost effective, acoustically effective and non-intrusive to the interior aesthetics.
After reviewing a number of commercially available acoustical materials, it was decided that a series of RPG barrier/diffusion and Johns Manville thick absorptive panels, plus solid barriers covered with an inverted curved/stretch fabric, would be effective in mitigating the high-energy acoustical transmission in the vaulted ceiling spaces. An air void behind the fabric also would be created for low frequency absorption.
These acoustical materials then would be layered over the existing, untreated gypsum board in the vault area. These diffusing and absorptive surfaces then would be covered with a soft fabric stretch material from Snap-Tex. This “stretch-fabric” approach would replicate the existing concave surfaces but without the disruptive acoustical properties of the previous untreated surfaces.
They selected multiple channel noise generators for the sound-masking system. A distinct and separate channel thus would be dedicated for each of the varying types of acoustical zones. The high vaulted ceilings would utilize a separate generator with a distinct output spectrum, thus creating a noise signature unique for that particular space.
Other Distinct ‘Signatures’
|The downtown Indianapolis skyline as viewed from the NCAA headquarters building.
Low ceilings in open office plans had other distinct spectrum signatures, with multiple attenuators in each zone. Larger areas typically would have a different spectrum than small areas, and zone attenuators were specified within zones to allow for further refinement of the levels required.
They specified Atlas Sound scheduling software that changes the masking sound signals according to the varying occupancy background noise. As the individual offices increase activity, the scheduling system would keep track and the generator output levels would be adjusted automatically.
Armstrong grid-type, masking loudspeakers were called for to be ceiling-mounted behind the stretch-fabric ceiling. Speaker density coverage also was increased significantly.
To avoid one of the problems that had plagued the previous system, the specifications mandated that security covers be installed on all equipment, security hardware be used to lock-down all calibrated adjustments and all power amplifiers be equipped with rear-mounted pots.
Implementing Corrective Procedures
Through a selective bidding procedure, the Mooresville IN-based acoustical contracting firm of Perry Acoustics was given the responsibility for implementing the somewhat elaborate system of diffusing, absorptive materials and the task of installing the new stretch-fabric ceiling. Indianapolis-based Fairchild Communications Systems was chosen to provide and install the new sound-masking system.
Inasmuch as the building was still a working entity, the timing and scheduling for the remedial work was accelerated. Both Bill McQueen, project manager for Perry Acoustics, and Chuck Fairchild, owner of the company that bears his name, remarked that, although the work schedule was tight, they were given the utmost cooperation from the owner, and their work proceeded in a relatively “sane” fashion.
David Wright observed, “Generally, [Wright Consulting] has found that a sound-masking system is relatively simple to install, but it must be precisely adjusted. It has to be ‘dead-on’ for each little area. Perfection isn’t quite close enough when it comes to matching acoustics to noise generators and attenuators; we find that most masking installation happily ignores this.” Nonetheless, he noted that, “In this case, the system provided and installed by Fairchild was a gratifying exception to many of our previous experiences.”
In the case at hand, a skillful blending of well-chosen diffusion materials, high-density sound masking and an aesthetically pleasing contoured fabric overlay mitigated the disruptive acoustical interferences while, at the same time, maintaining the integrity of the architectural design. This proved that solutions in such cases need not be architecturally obtrusive to be effective.
In Wright’s words, “Masking systems can increase employee productivity by elevating task concentration and offering speech privacy. These aims have been realized as a result of the renovation and, in addition, we were able to maintain a beautiful work environment.”
He added, “This project was truly an electro-acoustical solution instead of a sound system upgrade. We believe our industry often misses the mark when bid or design/build approaches don’t consider both the sound systems and the acoustics as part of a complete package.”
The problem has been essentially eliminated, the client is happy and the employees now are able to function in a normal fashion. Case closed.
Carson Design Associates
Steven J. Cain, AIA, CSI, CCS, CCCA, NCARB, is a senior architect and team leader with Carson Design Associates. He has a Bachelor of Science in Construction Technology from Purdue University and a Masters of Architecture from the University of Illinois. Cain’s more than 20 years of design experience on a wide range of projects has involved a number of corporate office projects with acoustical challenges.
Headquartered in Carmel IN with a branch office in Austin TX, the company employs more than 45 professionals. The firm’s offerings include architecture, interior design, warehouse and move management services, and web-based facility management tools. For project profiles, visit www.carsondesign.com.
Wright Consulting Associates, Inc.
Wright Consulting Associates, Inc. (WCA), is an independent consulting firm providing AV design and acoustical services since the late ’90s. The principal, David Wright, CTS, ASA, began work in an ANSI-calibrated acoustics lab in Boston after earning a degree in theater production and audio. He has been a contractor, manufacturer’s rep and musician, as well as editor of a book about professional AV presentation for the Eli Lilly Company.
WCA has completed more than 300 projects since 2001. Clients include architects, engineering firms, zoning boards, industrial, religious, theatrical and commercial accounts. The comp-any’s focus is on acoustic design opportunities that provide best results when approached early in the design process with an architect. Its banner is the incorporation of acoustics as a priority, along with sound and AV design.
WCA is particularly enthusiastic about noise masking, worship spaces and architectural noise control, as well as commissioning sound systems to their full potential.
Wright’s philosophy is to give a project the proper guidance and balance, so projects always will provide the best long-term reference.
35 Armstrong P-25 speaker, grid privacy style
8 Atlas Sound E408-3-RM 35W attenuators
8 Atlas Sound E408-75-RM 75W attenuators
30 Atlas Sound W-115 AT-WH speaker, surface style w/bracket*
50 Atlas Sound M812-S1-T7 speaker, tile support, transformers
Atlas Sound Plate-052 security covers, mounts
1 Atlas Sound MG1500 1-channel sound masking generator
1 Atlas Sound MG3001 multi-channel sound masking generator w/scheduling software
1 Middle Atlantic DWR-35-22 wall-mount equipment rack w/accessories
1 QSC CX-302/602V power amp w/security cover
1 SurgeX SA-15 AC surge protector
1 SurgeX SX115 AC surge protector
1 TerreSonde Audio Toolbox test equipment**
West Penn 25224 plenum speaker cable
West Penn 25291 plenum mic cable
3 Yamaha HX150 power amps*
Johns Manville 5" medium density rigid insulation/absorption material
700 Perry Acoustics custom 5" MDF barrier board fins
Perry Acoustics polyester stretch fabric panels
100 RPG “Skyline” acoustical diffusion panels
RPG “Flutter Free” hardwood diffusion treatments
SnapTex track system hardware
**For commissioning purposes only
List is edited from information supplied by Wright Consulting Associates, Inc.
Contributing Editor R. David Read has an abiding interest in architectural acoustics.