Mass Notification: A-Z

Recent public tragedies have often led to the lament, ‘If only there had been some way to warn people.’ New alerting technologies and systems are answering that need in a major way. Find out what you must know to tap into this growing market.

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Speakers themselves are undergoing a renaissance. In the past, the LSS market was concerned primarily with audibility. To pass inspection, the LSS had to be able to provide sound pressure levels (SPL) of 15dBA-fast over ambient SPLs; being able to understand the message content was not always the prime concern. Today’s market demands intelligibility — that the message is not only audible, but understandable as well.

Designing a system for intelligibility is easier said than done. The differences between an audible and an intelligible system design are many, but can easily be quantified by the number of speakers and their wattage taps. It is not unusual to need one speaker at a 2-watt tap for an audible design, but eight evenly distributed speakers at 1⁄4-watt taps for an intelligible design.

For more complex a
pplications, many systems integrators now employ sound modeling software to create a virtualization of the application to determine how the system will function once it is installed.

Systems contractors must now pay very close attention to the physical surfaces in the areas served by the systems they install. Changing a floor finish from carpet to ceramic tile will have an impact on the acoustical characteristics of the area — it may make the signal more audible (louder), but will also make it less intelligible. These changes are generally resolved by change orders and system redesign and will need to be addressed early in the design process, long before the system is completed and tested.

LSS have been primarily concerned with just the interiors of facilities. With MNEC, that is no longer the case. Military bases, campuses and other multi-structure facilities with adjoining grounds also need to get signals to people on those grounds. These applications call for special application appliances called high power speaker arrays (HPSA). These units, as their names imply, are extremely powerful assemblies of amplifiers, speakers and control equipment.

As a point of reference, a standard LSS speaker may produce 90dBA-fast at 10 feet and serve an area of roughly 1,000 square feet. HPSAs, which can only be used in outdoor applications, may produce 130dBA-fast at 100 feet (or roughly 145dBA-fast at 10 feet) and serve a radial mile. Comparing wattages, an LSS speaker may have a 2-watt tap, while the HPSA may be set at 3,200 watts. Special safety procedures must be used when installing, operating or servicing these units.

Prerecorded messages are best, but the systems must also support live paging Areas with multiple language needs may also require messages to be broadcast in those respective languages.

With MNEC systems, visual signals are also key to notification. While the standards may permit clear lens strobe lights for both evacuation and emergency signaling, most systems today are installed with clear lens strobe lights for evacuation and amber lens strobe lights for emergency or alert signals. Only one strobe light color is activated at a time. Furthermore, in addition to dual-colored lens strobe lights, textual visual signs are also being used in many applications.

Once the Tier 1 applications are addressed, Tier 2 notification should be evaluated. Tier 2 systems are also referred to as distributed recipient mass notification systems (DRMNS). Unfortunately, there can sometimes be a tendency among clients to jump to Tier 2 without adequately addressing Tier 1 needs. Some end users feel once they have deployed an SMS text messaging system (messages to cell phones) they are all done with MNEC. This can lead to a false sense of security as it does not address situations in which the cell phone is off, the provider is off-line or the tower is off-line.

Tier 3 applications usually consist of providing and installing local displays and/or interfaces to site television or radio systems. These systems are also used for nonemergency notification, such as time, company announcements, etc., which makes this type of system more attractive to facility operators.

Using, Evaluating the Solution

Once the action plan has been done and the systems designed, system operation must be evaluated. In many applications, MNEC signals can actually override LSS signals. This is a radical change in the thought process of system owners, operators and AHJs.

In addition to evaluating system signaling priorities, consideration should also be given to where the controls are located and who operates the system. Once the situation has been validated, MNEC systems are usually operated manually. This requires close coordination with first responders, AHJs and facility operators.

In closing, systems integrators that are ready to develop the proper skill sets, and take the time to educate and nurture their client bases, can excel in the new and exciting MNEC market – while providing a valuable solution to their customers.