Hendon Publishing - Article Archive Details
PA Systems for Training and Simulation
Public address (PA) technology has long been valued as a way to inform and protect a targeted group or audience, from directing crowds in general situations, to crisis response and intervention. The value of the PA system remains significant for targeted and mass notification, but that value extends to other applications. Officer training is one such application in which PA systems are regularly used to broadcast range commands and create simulated environments based on voice and other aural directives.
Law enforcement agencies have various choices for public address systems in training and simulation applications. For audio reproduction, the choice often boils down to the use of full-range loudspeakers and high-efficiency horn systems. There are immediate, remarkable differences in audio quality, speech intelligibility, durability, functionality and setup and logistics. The choice of a PA system will ultimately determine the overall effectiveness of the training and simulation program based on these attributes.
Loud and Clear
Volume is an essential element for training and simulation programs in law enforcement. However, volume alone doesn’t suffice. It needs to be loud, but it needs to be clear. The desired result is not achieved without intelligibility. There is a critical difference between sheer volume and intelligibility, and that difference can either drive or impede the success of the program. Audio horns certainly provide plenty of volume and in fact make quite a racket. They work fine in some circumstances, notably the generation of sirens and warning tones with limited frequency ranges, and blasting them over long distances.
The real challenge comes in reproducing voice for training and simulation purposes. Consider some basics of a range-based training program that include weapon extraction and control, loading and unloading of ammunition, firing mode and repetitions and movement with drawn weapons. Horn systems have an unfortunate tendency to poorly reproduce speech, delivering distortion as opposed to clarity. The ability for participants to clearly understand the voice emanating from the PA goes a long way in ensuring that instructions are heard and followed.
If the PA system doubles as a Giant Voice communications system, unclear sound quality is potentially problematic on other levels. Giant Voice systems require clear speech to deliver critical life-safety warnings, communicate the location of potential threats, or convey important instructions to law enforcement officers and/or the public in crisis situations.
Well-designed loudspeakers supply both volume and intelligibility. The tinny sound and harsh distortions that emanate from the conventional audio horn are not only unpleasant, but often incomprehensible. Horn designs frequently have narrow coverage angles, turning the horn into an acoustic “spotlight.” Those directly in line with the horn are blasted with sound, while those to either side of the horn experience difficulty in comprehending important commands.
Wider dispersion loudspeakers, such as those manufactured by Technomad, also offer a clear improvement over the narrow-beam width of horn devices. These may have 120 degrees of horizontal coverage by 120 degrees of vertical coverage for very broad dispersion, and 60 degrees by 40 degrees for narrower fields with fewer targets. This ensures that officers can hear commands at short, medium and long distances, and can follow instructions accordingly.
System Design and Integration
A quality PA system will include several integral components beyond the loudspeaker. The majority of these additional components are best centralized in a self-contained equipment rack, mounted or otherwise situated in a protected environment. Components typically include an amplifier to power voice and audio over the loudspeakers; a mixer to manipulate various levels; and reliable source equipment to handle playback of recorded audio clips that might play a role in training and simulation programs.
It makes sense to first consider the projection, as the system is only as good as the end point. The loudspeaker is the delivery method to the audience, and strategic planning as to the number of loudspeakers required to achieve the desired audio result is critical. The size and scope of such a system, depending on the area being addressed, is scaled with relative ease by adding loudspeakers at strategic points and/or linking multiple systems to the main PA.
Quality loudspeakers will deliver intelligible speech and audio in the half-mile to one-mile range, which will cover a majority of training and simulation environments for local and state law enforcement. Two to four loudspeakers tied to a central signal processing system will suffice to cover such applications in 180 (directional) to 360 (omni directional) degree areas.
Speech and audio delivery from the signal processing rack to the loudspeakers can be handled over cabled infrastructure using Ethernet/IP, twisted pair or optical fiber lines. Wireless RF transmission is also a possibility, although this is more common in the military. Wireless RF transmission also delivers the possibility of tying in land-mobile radios for long-distance communication in training and simulation. Twisted-pair connectivity may be ideal for indoor and smaller outdoor spaces, while programs requiring large open spaces may benefit more from IP or Wireless RF connectivity.
Government agencies, academies and perhaps even local or state law enforcement agencies require systems that cover a larger area and therefore will require a building-block system that ties multiple remote PA systems back to the main system. Distribution systems such as Technomad’s Twisted Pair, Ethernet and Wireless Link Kits or Twisted Pair Link Kits offer CD quality audio over long distances back to the main PA.
The Twisted Pair offers quick set-up at a low cost compared to traditional telephone copper wire or multi-conductor CAT5 wiring, generally ranging up to three miles in point-to-multipoint or daisychained deployments. Ethernet/IP offers excellent audio quality and zone control capability for audio levels at multiple points. This is also an ideal opportunity to take advantage of existing network bandwidth.
Wireless is ideal for distance. It helps to have robust connections with links ranging to 15 miles and flexible systems with quick setup, high-quality audio, minimal delay and zoned audio control capability. Zone-control capabilities in large Ethernet and wireless systems allow system operators to stream or transmit voice and audio to specific remote PA systems in the multipoint design, or allow the delivery of an “all-call” message to every loudspeaker in the system.
The human voice is likely the main audio source for training excercises. However, any number of training and simulation exercises, from weapons training to civilian-oriented programs such as crisis intervention and building evacuation, may benefit from audio beyond the live human voice.
Because police departments are often first on the scene in crisis situations, training is imperative to ensure that officers gain the skills to work through sensitive situations with offenders and their families. Simulation is ideal for creating a realistic environment from the initial response through to the conclusion of the situation.
The PA system is instrumental to injecting realism into simulated events. This may include the use of gunfire, alarms, sirens and other audio cues relevant to a training exercise that reflects a real-life emergency situation. Compact disc players, mp3 players and iPods are often integrated into the signal processing rack to accommodate additional audio elements. Technomad also offers a unique 1RU MP3 playback and recording system called the SuperConductor.
Developed specifically for military and government applications, the unit combines the easy, on-demand playback of an MP3 player with sophisticated automatic playback capabilities. It removes the need to fumble with compact discs in training and simulation programs, enabling a cleaner playback system. It also stores hours of audio files that can be manually played back from a front panel push-and-turn knob. It can act as a scheduled audio playback system and message repeater for both training and simulation, as well as in emergency and general audio playback applications.
Dual Functionality and Durability
A reliable PA system can serve multiple purposes, whether used for temporary applications or as a permanent, fixed system. Depending on the size of the system, local law enforcement agencies may find additional benefits for officer alerting, general paging and large meetings, as well as for social occasions such as ceremonies and community events.
Above all, system durability is an absolute requirement. Weatherproof loudspeakers are ideal for outdoor installations to cope with rain, snow, sleet and water ingression. Equipment that cannot survive the rigors of wind, impact and other abuse will degrade over time, whether used in temporary or permanent applications.
Training and simulation is more important than ever in law enforcement. In addition to weapons training and crisis intervention, training in civilian relations is critical considering the threats of retaliation against officers, departmental lawsuits due to use of force and other unfortunate possibilities.
Law enforcement agencies today have more choices than ever to customize effective PA systems that meet various training and simulation goals. Reliable and durable PA systems that provide intelligible audio go a long way in benefiting every officer in the program.
Rodger von Kries is the vice president of Technomad, a leading manufacturer of weatherproof loudspeakers and audio systems.
Published in Law and Order, Apr 2010
Rating : 10.0
Click to enlarge images.