Originally published in the March 1996 issue of:

scnlogo.gif - 4.5 K

The Paging System Blues

by Barry McKinnon

of Mc2Systems Design Group

Paging systems have been around for, what, six decades now, and they still seem to be an insurmountable or intractable design problem. The paging system design itself is not all that challenging, but it seems that everything else attached to the paging system still exhibits the same problems that have plagued them for sixty years or more. I'm referring to the environment that paging systems are placed in, whether that is indoors or outdoors. Paging systems are still considered as a fairly low priority in the overall building or facility design process. Even when the paging or public address requirements are a priority for the facility owner, many (most?) design teams are not interested in hearing about the factors related to the performance of a paging/public address system if it will impact the project's appearance, costs, or the conceptual plan that is already being developed (with a substantial inertia all its own). It may be that I just run across a lot of these projects, and the rest of the contracting and consulting world actually moves along smoothly, in a warmly cooperative relationship with their design teams and facility owners.

The sort of problems I'm talking about are nothing new to the sound industry, in fact these problems are as old as the sound industry itself. Excessive reverberation time, with no will or interest in correcting same; inappropriate loudspeaker locations dictated by aesthetic design constraints; or inadequate loudspeaker coverage due to either physical or monetary restrictions on speaker count or selection; these are all typical problems we face as system designers. While these complaints might have become the equivalent of any sixty year old's constant description of aches and pains, we, as an industry, need to find a way to get the other design disciplines of architecture and engineering to listen to our complaints, instead of blissfully ignoring them. Every time we fail to deliver the system performance that we know should be provided, but won't be, due to compromises made for us by others, we do a disservice to ourselves and to the facility owner. We perpetuate low expectations for public address and paging system performance, and we risk compromising the function of a facility.

will the owner of a blue...

The rest of the design team will walk away from a project that looks nice, is well lit, has efficient air conditioning, has elevators and escalators that meet code, won't fall down in an earthquake, but just happened to have a mediocre public address system because the budget was slashed in half to save money. The owner is left with a facility that meets all his criteria but one, people can't use it because the paging/public address system is not up to the task. You can be sure they will remember which consultant or contractor was responsible for that part, long after they've forgotten who laid out the lighting.

For the most part, a paging/public address system seems to be viewed in much the same way as the office furniture or the venetian blind contract. It is just another contractor that shows up near the end of a project, gets in the way of the painters, and creates coordination headaches when they've only got two weeks to finish a building. Because there is no requirement for an effective paging/public address system in the building code (unlike the life safety paging system), the paging/public address system exists only as part of the owner's requirement section of the project in the minds of the architects and planners. In light of the ADA requirements, and similar National Building Code of Canada requirements for accessibility for the hearing impaired, it is ultimately ironic that no equivalent requirement exists for the disability challenged (that would be people without hearing loss). There are no requirements to deliver a facility that has usable acoustic performance, or an intelligible sound system, even though the criteria that would define both are well established, measurable, and can be predicted in advance of construction.

It still surprises me when I find that other design professionals are unaware that sound system performance can be predicted prior to construction. Architects, electrical, mechanical and structural engineers that work with computer design systems on a regular basis are downright amazed when you tell them you can model sound systems in anything as simple as a spreadsheet to a full 3D CAD program. It surprises me even more when I find that some of these design professionals are designing paging systems using something akin to rune casting. Using an approach similar to lighting instrument layout, many paging systems are designed by a simple scattering approach, so many speakers for so many square feet of floor. There is no consideration given for the reverberation time of the space, the background noise levels, or even the presence of adjacent objects or barriers. These are considered to be problems for the sound contractor to deal with on-site. We recently reviewed a paging system design for a lobby of a building that was approximately 130 feet long, 25 feet wide and 18 feet high, with a reverb time in the 3 second neighbourhood, and equipped with five wall mount 8" speakers at 16 feet above the floor, pointed straight across the lobby at the glass wall opposite. What would your best guess be of the expected performance of that system. The worst aspect of this review is that it happened after the tender date, and there was no plan to implement corrective measures, even after it was flagged for the design team.

The other disturbing design approach is the incantation. A design that worked in one project is repeated verbatim in every subsequent project, without regard to any differences in the requirements of the system or the spaces it would be used in. Sometimes these incantations are written by a sound contractor for the design professional, and the incantations are faithfully memorized for future use. Many times the sound contractor will not have been fully informed of the conditions that the system will be required to work in, or it may be a sound contractor operating beyond their experience, and the incantation will be flawed. We were involved in a project where the electrical engineer had developed a general design layout based on a similar system in another location. This was a large scale system, with large pole-mounted outdoor speaker systems on one side of the field to be covered. They had provided for signal delays to align the signal along the line of poles (Like the other system they based it on, which was in a parking lot), but had neglected to consider the 300 foot deep coverage area, and the inevitable overlap between delayed systems at the furthest point across the field. In this case, there was an incomplete understanding of the function of the signal delays, and that led to an inappropriate system design. By the time the difficulties were pointed out, the project was so far along that mounting pole positions were fixed, and significant changes to the design were required to accommodate the existing pole mounting. We were reviewing this particular system design for noise intrusion into the surrounding area, not for the speaker system design.

Another example that springs to mind was a huge industrial building with a calculated reverberation time of 6+ seconds that was to have a paging system installed. The design team had input from an industrial acoustics consultant who indicated that they should have the paging system design reviewed to evaluate the expected speech intelligibility. The design was to be distributed re-entrant horns mounted on the 30 foot ceiling. The design professional responsible indicated that they regularly do sound system design, but not in difficult spaces like this one. The temptation to ask how they design the systems for the less difficult spaces was tremendous, since the process is the same. In this situation, it was too late to install affordable acoustical treatment during construction, and there was no budget for retro-fit treatment. The concern for the paging system performance arose because of the owner's dissatisfaction with a similar building and similar paging system, not because someone recognized there was a problem with the new one. They at least recognized that they couldn't tell if there was a problem. There was, of course, a restricted paging system budget, and one that only would have worked if the room would have had much better acoustical performance.

The point behind this rant is that paging/public address system design is as much a professional discipline as any other aspect of the design of a building or facility. How is it that design professionals that would never consider crossing over into other design disciplines (such as electrical engineers doing structural design, or architects doing electrical design) seem quite at ease designing a sound system without an understanding of the critical parameters for successful design. Most rooms that require a paging/public address system, require that system to be an integral part of the room's function. If the system doesn't work, then the facility design fails to meet the user's needs, just as thoroughly as if it has poor lighting, or poor air conditioning. Aside from the liability issues that arise from stamping drawings that represent a design that has been produced without full understanding of the design issues, there is the professional responsibility to the owner to deliver a professionally designed facility. There is nothing professional about designing by guesswork.

While the systems contracting industry is trying to establish professional standards for contractors, in an effort to ensure that there is some measure of consistency to systems contractors, there seems to be no easy way to make the same point with the design professionals responsible for the entire project. To acknowledge that my tar brush is not infinitely wide, there are many architects and engineers that recognize the need for a system design specialist, or who have fully qualified people on staff for the design of sound systems for paging/public address. It would be safe to say that these are a minority of the designers out there.

The question is what to do about the situation, and how to go about doing it. The current economic climate has the architectural profession working on really tight margins to stay busy. As one architect told me, they are having to bid so low to get the jobs, they can't afford to invest the time into the job to do the work that is required. This is why coordination is left to contractors on-site, and this is why there is no extra design budget for specialty consultants unless specifically required by the owner. It seems to be a poor time to start trying to push for a demonstration of professional responsibility when the fee budgets barely allow for the minimum responsibility required to get a building into the air. Large firms and large projects will not suffer to the same extent as more mundane projects that make up the majority of construction, but small budget sound systems still deserve the same performance as large budget sound systems. Low budget ears work pretty much the same as large budget ears.

This is obviously not an afternoon project, this would require some moving and shaking on a grand scale. We, as an industry, need to educate the design professionals as to the extent of their professional responsibility in delivering a viable speech intelligibility environment, and we need to get some standards in place so that delivery of reasonable performance from a paging/public address system can have the same weight applied to it as delivery of performance from an HVAC system or an elevator. This has to take place on several fronts at once, approaching the design profession, the building industry and the regulatory bodies.

While the efforts of the NSCA to improve the standards of systems contractors is a major step in the process of establishing greater responsibility for the work being done, it would appear that there needs to be a similar educational campaign started with Architectural Institutes and Engineering Associations to help make it clear that there is both an implicit and explicit responsibility in the design of any acoustical environment and any sound system, and that the responsibility extends to ensuring that the design is done to the same calibre of rigorous professional standards that any other aspect of facility design must pass. That is, clearly defined design goals are laid out, based on established minimum performance criteria, and the design is developed using sound (pardon the pun) engineering practices to meet or exceed those design goals.

This would obviously require the involvement of all of the audio and acoustical industries, and the related associations to be effective. We would need not only a consensus of what the minimum standards were to be, but complete support for the establishment of the standards. The first complaint I would expect to hear from anybody is that it would increase the cost of construction. The point is, it wouldn't increase the cost of construction if there was an intent to do it right the first time, a successful sound system design costs what it costs to make it work. If the system was value engineered by the designer, then it is as cost effective as it can possibly be to deliver the performance required. If the sound system budget suddenly can't be arbitrarily cut to allow for solid brass hardware fittings instead of brass plated fittings, then it is the brass fittings that raise the cost of construction, not an effective sound system operating in well behaved acoustical environment. It would mean that building budgets would have to contain the real costs for sound systems, and the design team could not shuffle that budget amount into the separate owner-purchased column. It would also mean that the designer of sub-standard sound systems would be required to make good on poor design.

Perhaps this is all just a fever dream after a week of working to produce system designs that work in spite of limited budgets and goofy restraints on speaker placement, or reviewing peculiar system designs by others, but I think it really is time we started taking the guesswork out of sound system design, and, more importantly, taking the guessworkers out of system design.

Return to the Systems Contractor News Article Index

Return to Barry McKinnon's bio

Return to the Mc2Systems Design Group main page

Systems Contractor News
a United Entertainment Media Publication

United Entertainment Media Inc.
460 Park Avenue South, 9th Floor
New York, NY, 10016
Ph. 212-378-0400
FAX 212-378-2160
by e-mail