Written by Troy Jensen,

AN ARCHITECTURAL GUIDE TO SUCCESSFUL CONFERENCE SYSTEM DESIGN

AN ARCHITECTURAL GUIDE TO SUCCESSFUL CONFERENCE SYSTEM DESIGN

The technology of building design and of the conference systems we install in them have both changed significantly since architect Louis Sullivan coined the phrase “form follows function.” Sadly, we often see that the lowly conference room gets minimal infrastructure review during design, more often than not taking a second seat in the design of the modern office.

At various trade shows and industry gatherings, I often hear the comment, “If I had only known then what I know now.” Interestingly enough, this is usually not about the technology in the conference space, but is rather a reference to the base building design and its effect on the quality of audio and video conferencing.

The Shure MXA910 answers the age-old question of whether microphones need to be on the conference room table. Prior to this product, the answer was generally “YES” if clear speech was the goal. The MXA910 is a ceiling-mounted directional microphone array with Steerable Coverage technology. Its adjustable pattern control allows you to tailor the coverage of the product to fit your conference arrangement. It also has the ability to store recallable presets if your room configuration needs to change. It can also assist with limiting the amount of ambient noise picked up within the room by focusing only on those areas where speech needs to be targets – ignoring areas with no desired sound source. This improves the direct-to-ambient sound ratio, improving intelligibility. As a bonus, it also eliminates having to drill holes in your table and/or floor for cable runs.

Room size and shape, acoustical treatment, and HVAC (heating, ventilation, air conditioning) are all important factors in the successful implementation of audio conference systems. Ideally when designing a conference space, you would enlist the services of allied professionals, notably an MEP Engineer (Mechanical, Electrical, and Plumbing) along with Acoustical and Audiovisual Consultants. But often we are asked for assistance in the commissioning of conference systems where key professionals were not consulted. For those spaces where the architect or owner are left to design the space on their own, we offer the following guidelines and product ideas to help overcome such deficits.

One of the most difficult challenges we encounter is dealing with too much ambient noise, typically caused by ill-designed HVAC systems. Noise curves are a common way to measure and specify background noise in unoccupied buildings and spaces. Their purpose is to produce a single value representation of a complete sound spectrum.

There are various noise rating methods for determining the ambient noise level of a room, including Noise Criteria (NC), Noise Criteria Balanced (NCB), Room Criteria (RC), Preferred Noise Criteria (PNC), and Noise Rating (NR) curves. For the purposes of this discussion, we will be focusing on NC (Noise Criteria) rating.

The Noise Criteria (NC) rating of a space is defined by the lowest curve that is not exceeded by the measured spectrum and any point in the audio frequency range. NC ratings are categorized in increments of 5.

Typically, two noise issues can be created by the HVAC system: mechanical noise from the equipment itself, and noise created by the air speeding through the ductwork. Mechanical equipment noise from fans, chillers, pumps, and dampers can be mediated by locating them as far from the conference space as possible – something often not addressable in a completed building.

The effects of noise created by high air speed can, however, be reduced. Oversized ductwork (preferably lined) should be employed, allowing the system to maintain the desired room temperature while keeping airspeed to minimum. Ideally, an NC target of 30 or less is desirable for a conference space audio/video system where microphones will be deployed. Both supply and return ducts need to be reviewed with respect to length and size in noise evaluation.

The size and shape of the room under design should be reviewed with an eye on function and occupancy. Where wall surface space allows, acoustical materials should be employed. Today, a multitude of effective interior acoustical treatments are available, making it possible to create a more acoustically inert conference room with an acceptable aesthetic look.

The recent trend toward acoustically reflective glass walls in conference rooms makes the room more reverberant while reducing the wall surface area available. Thus, any available wall surface should be considered for treatment with absorptive materials. Acoustical tile ceilings and carpeting are also beneficial in this respect.

Conference room wall construction is another important factor, and is often effected by the functions of surrounding spaces. If the conference space is located adjacent to a mechanical equipment room, it will require a higher Sound Transmission Class (STC) partition than if it is next to a storage closet. Doors and windows must also be carefully considered with respect to the required acoustical isolation. Matching the STC rating of your walls is important in maintaining the room’s desired Noise Criteria (NC) rating.

Sometimes the offending noise source is outside of the building in the form of mechanical equipment, sirens, traffic noise etc. These offending noise sources (outside walls/windows) should be considered when determining where to place a noise-critical space like a conference room on your floor plan.

Some form of absorptive treatment is recommended for the walls of the conference room under design. A target of about 50% of the wall surface is a good start. This can be traditional absorptive wall treatment such as panels or thick felt wall coverings. These treatments go a long way in improving the audio quality of conferences.

The use of multiple layers of drywall and semi-rigid fiberglass fill improves the Sound Transmission Class (STC) value of the wall. Choose your partition detail on isolation required, based on room adjacency and acceptable sound transmission between those spaces.

Steerable array microphone systems, such as the Shure ceiling-mounted MXA910 and table-mounted MXA310, are capable of rejecting excessive HVAC noise. Their steerable pickup patterns can be a huge help in retrofitted rooms where construction options are limited.

The use of multiple layers of drywall and semi-rigid fiberglass fill improves the Sound Transmission Class (STC) value of the wall. Choose your partition detail on isolation required, based on room adjacency and acceptable sound transmission between those spaces.

The MXA310 easily covers what would ordinarily require at least 4 microphones, thus reducing the number of penetrations/devices required on the conference table. This multi-mic desktop device has the abilities to select multiple polar patterns – including a unique toroidal shape – and adjust its aim. By enabling post-installation adjustment of pickup pattern, coverage can be optimized and room noise rejected, even in changing room configurations.

Steerable array microphone systems, such as the Shure ceiling-mounted MXA910 and table-mounted MXA310, are capable of rejecting excessive HVAC noise. Their steerable pickup patterns can be a huge help in retrofitted rooms where construction options are limited.

Networked conference systems, automatic mixing, and Dante-enabled wireless systems now work together. As a result, the quantity and type of cabling required has been simplified and, in many cases, eliminated. This reduces the need for cabling infrastructure and means fewer core drills and wall penetrations. It all contributes to improved acoustical performance and lower install cost with respect to the base building work required in the install of these systems.

The use of Dante-enabled wireless conference solutions such as Shure’s MXW and ULX-D systems provides the ability to deploy microphones where needed without having to alter the existing architectural infrastructure. Eliminating core drills and wall penetrations maintains the room aesthetic and acoustical integrity while providing the ability to deliver clear and intelligible audio.

Proper application of advanced audio technology can alleviate some of the architectural and engineering issues described above when, ideally, the source of the issue should have been addressed in the design/build phase of these spaces so that the technology could excel in its role.

Acoustic design and noise control consultant and application specialist Patty Gaus, principal of St. Louis based Gaus & Associates Sound Control Solutions, notes that when a conference room system is under-performing, the owner typically points to the equipment and/or system provider as the problem. Often, however, the composite room construction and interior finish conditions are the real culprits. Unfortunately, when a space is being designed, little consideration is given to how a space sounds and takes a back seat to aesthetics.

Gaus agrees that rarely can an audio/visual system stand alone without some type of absorptive materials. While carpet, upholstered furniture, ceiling tiles, or curtains help support the performance of the system, oftentimes, additional acoustic applications should be integrated into the room design to support optimal performance of the system. These factors are best addressed in the design phase – a luxury we don’t always have.

The Shure P300 IntelliMix audio processor provides automatic mixing for up to eight networked microphone sources, including wireless. Its small footprint allows discreet mounting under a table, in a credenza, behind a display, or in a rack. This simplifies installation by minimizing cable routing, lowering infrastructure requirements for conduit, core drills, and back boxes.

Once the base building features are in place, it is nearly impossible (financially and/or logistically) to make the changes necessary to achieve suitable performance. It is always best to enlist the services of MEP, acoustical, and AV professionals to assist with some of the details of conference room design, but the information above should go a long way in helping to avoid some of the pitfalls in the design of your next conference space.

About the Author

About the Author

Troy Jensen

A 30-year Audio/Video industry veteran, Troy has held numerous high-level consulting and management positions focusing on architectural acoustics, system design, and project & business management. He is also certified on several computer modeling and evaluation techniques for AV sound spaces, which is particularly helpful when serving as a guest lecturer in the Yale School of Drama M.F.A. program for Technical Design and Production.

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