In present day scholastic environments, school administrators are often under the gun to use existing facilities in ways they were not originally intended for. A typical example is the school gymnasium — where parent/teacher gatherings, commencement ceremonies, special announcements and other events are held when no dedicated auditorium is available.
Such events fall well outside of the gym’s original purpose, which is that of scholastic sports. But by knowing in advance that such cross-utilization is likely, and in many cases ultimately inevitable, the school can take measures to ensure that the sound system will satisfy the demands placed upon it. This applies equally to new construction, as well as to sound system upgrades in existing facilities.
Sports announcing is not a critical application in the K-12 realm, and may not exist at all. Conversely, the clarity and intelligibility of the spoken word at a graduation ceremony or a PTA meeting is very important and can make or break the success of the event. It’s essential that the presenter is clearly understood in an acoustical environment that is almost always sub-optimal for speech intelligibility.
The first thing to recognize is that the acoustical conditions in virtually any K-12 gymnasium are going to be terrible. The building was simply not designed for sound, but rather for sports. The hard floor surfaces, hard wall surfaces, wooden bleachers and the ceilings (likely to be untreated with dampening materials), will all cause acoustic reflections that make it very difficult to convey the spoken word intelligibly.
One possible cure would be to apply a very large amount of sound absorbent material to the reflective surfaces, but this is likely to be a poor solution because of cost. A typical K-12 gym might need several hundred thousand dollars worth of sound absorbers to make a significant improvement, but even that might not be enough to solve the acoustical problems.
Instead, capitalizing on the latest leading-edge sound system technology makes much more sense. A relatively new breed of loudspeakers that are known as “column line arrays” has entered the market in the early part of this decade. Column loudspeakers use the “line-array” principal to tightly focus sound energy where it’s needed. The line array principal forces otherwise conically radiating cone drivers to radiate as a “line source” in the axis in which they’re stacked one upon another (See Photo 1). Working together as a line source, the column of drivers radiates sound energy in a narrow dispersion pattern. The actual pattern is a function of how lengthy the column is; the taller the column, the narrower the dispersion pattern. The benefit of a well-designed columnar loudspeaker is the ability to direct sound where it’s needed and away from surfaces that cause reflections that damage intelligibility.
High-quality column loudspeakers are available from many well known manufacturers such as Community, Renkus-Heinz, JBL, Bose and many others.While each brand, and even each model,may vary in specific performance characteristics — and marketing claims — the common denominator is that a well-engineered column loudspeaker presents a narrow and controlled dispersion pattern, virtually the opposite of a conventional loudspeaker, which radiates sonic energy in a conical pattern from its low-frequency driver.
Conversely, the vertically stacked line array drivers of a column loud speaker provide pattern control that narrows the vertical dispersion in proportion to the height of the column. The coherent sound of the columnar line array source reaches the listener first — before the reflections are heard — making it possible to hear and understand what’s being said without needing to dampen the reflective room acoustics.
Location, location, location
Columnar loudspeakers are not necessarily expensive(though some can be), but because of their distinctively narrow dispersion properties, they must be located where they can be properly focused to cover the audience, not in some generic location at the back of the gym and pointing in the wrong direction. Most suppliers of these products can offer skilled advice to aid in the installation process.
In many cases, the best solution is to deploy the column loudspeakers on portable speaker stands, so that positioning can be adjusted appropriately for each type of event. This will also reduce the cost of installing permanent wiring and mechanical installation work. When not being used in the gym, the same column loudspeaker system can be stored in a utility room, remaining available for events outside of the gym, such as a warm weather gathering in an outdoor courtyard.
Ken DeLoria is senior technical editor for Live Sound International and has had a diverse career in pro audio over more than 30 years, including being the founder and owner of Apogee Sound.