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Sound Systems: Difficult Environments
Much of a sound system design engineer's problems deal directly with the problems that the room itself creates. For example, if the room is very "live" with excessive reverberation, more directional speakers are required for adequate speech intelligibility. Here are some special situations in which the sound system is located in an environment that creates unique problems. Natatorium Okay, okay. We're talking indoor swimming pools. But I just had to use "natatorium". It's so majestic. Besides, I heard an architect use it and he sounded much more credible. The important question is whether the plural of natatorium is natatoria or natatoriums. Any Latin students out there? Well, back to reality. In some ways a natatorium is very similar to a gymnasium. The walls are usually hard, which reflect sound waves, and the water itself is naturally reflective. Also, the walls are usually smooth and painted so they can be kept clean and free of mildew. This increases the amount of sound reflection or reverberation in the room. In order to overcome this reverberation, highly directional speakers are needed. | 
| The loudspeakers must be designed and built for high humidity situations. | 
| Swimming areas are also very humid. This environment is very hard on sound system components. The loudspeakers must be designed and built for high humidity situations. This means that the housing is resistant to the effects of moisture and the speakers themselves will not corrode. The water also presents an additional barrier. When swimmers are underwater, they can't hear the sound system very well. This means that coaches' instructions will be hard to understand. In the case of synchronized swimming, music and timing cues will be difficult to follow. In these situations, underwater speakers can be installed. An additional benefit to underwater speakers is their accuracy during synchronized swimming. Since sound travels faster in water than in air, the swimmers will be in much tighter sync with the music cues. These devices are specifically designed to be installed in the side walls of the pool underwater. An experienced contractor is required to install these speakers correctly and safely. A health and safety inspector is needed to approve the preinstall design and the completed project. Microphone Selection. Another often overlooked facet of sound systems in swimming areas is the proper selection of microphones. Three criteria must be met: |
| The first issue is safety and code compliance. |
| The first issue is safety and code compliance. Local authorities may not take kindly to a microphone cable being strung across the pool or wet floor. You must make certain that ALL elements of the sound system are properly grounded. Furthermore, if the electronics supply a DC voltage of 48 Volts for condenser microphones, some inspectors/local codes may consider this to be a problem. A safer bet is to use dynamic microphones rather than condenser microphones. The second issue is functionality. The best microphone system to use for swimming areas is a wireless microphone, especially in instructional situations. This gives the instructor/coach total freedom of movement. This approach is also the best safety solution. Most belt pack transmitters use a single 9 Volt battery. |
| Dynamics are less susceptible to failure or damage due to high humidity environments. |
| The third issue is the durability factor. Whenever possible, use dynamic microphones rather than condenser microphones. Dynamics are less susceptible to failure or damage due to high humidity environments. This also applies to wireless lapel microphones. A dynamic lapel mic may be larger and bulkier, but it will outlast an electret condenser lapel mic in this environment. You should also rely on an experienced contractor to choose the best wireless system for this application. Ice Arenas Sound systems must overcome the same problems in ice arenas as they do in natatoria, including humidity. In addition, they must be resistant to the occasional hockey puck or stick if the ceiling is low enough to present this possibility. |
| Outdoor speakers are constantly bombarded with rain, snow, ultraviolet radiation and other extreme... |
| Outdoor Stadia Similar problems affect outdoor sound systems for stadia. In addition to the drastic changes in humidity and temperature, outdoor speaker systems are also subject to elements unique to the outdoors. Outdoor speakers are constantly bombarded with rain, snow, ultraviolet radiation and other extremes such as wind. There's nothing more aggravating than to fire up the stadium system in the fall only to find that the speaker enclosure is filled with rainwater from summer storms or that birds have nested in the speaker openings. Certainly these systems require specific design and component selection, as well as experienced installation in order to ensure that the system performs well over the long haul. Local ordinances may also require special attention to the environmental noise issues regarding sound "drifting" into residential areas. Here are some tips for outdoor speaker systems: - Test the system two weeks prior to the first event in the fall.
- When first firing up the system after a seasonal lapse of use, turn on the system with all volume controls turned down. Allow the system to idle for several hours to "burn off" any moisture before hitting the system with any appreciable signal.
- If at all possible cover all speaker enclosure openings with a weather-resistant screen such as chicken wire to prevent "creature nesting".
- Check all speaker mountings to make certain that nothing has shaken loose due to wind, etc.
- If you're not certain about any of this, call us!
Open Classrooms At first glance, you may think that classrooms do not present difficult environments. To quickly dispel any doubt simply envision a student jamming a pencil, pen or some other utensil through a speaker grill just to see what will happen. Enough said. Other than the obvious physical destruction elements, open classrooms present another specific environmental problem. Any sound allowed to "spill over" into another classroom may be an unwanted distraction. The simple solution here is to design the speaker system with high quality components mounted in the ceiling. If these components are distributed correctly and aimed toward the floor, overall sound level can be lower in level while maintaining adequate performance. This approach will also minimize the amount of sound that affects other classroom areas. This type of system can also greatly improve the quality of sound for any video or film projection. by Travis Ludwig © 1996 Internet Sound Institute (www.soundinstitute.com). This article is for personal use only. Any commercial reproduction is not permitted without permission. To obtain permission, contact ISI at hopi@soundinstitute.com
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