Over the last three to four years, mass notification has become established as a standard required functionality for a comprehensive security and life safety program. Once considered appropriate only in the limited domain of high-pitched tornado warning sirens, current systems offer the complete range of notification tools in addition to online collaboration sites acting as virtual emergency operations center.
Crisis management professionals clearly agree that the ability to efficiently and reliably communicate with the affected population and the responding agencies is foundational to rapid and efficient crisis resolution. Any limitations in the ability of the crisis management team to communicate with the responding agencies invariably results in an inefficient and uncoordinated response. Pragmatically speaking, an inefficient response means lives are lost.
At its core, mass notification is the collection of technologies designed to provide information in near real time in response to, and management of, an off-normal event.
Interior and Exterior Broadcast Loud Speakers
This option is an extension of the emergency duress telephone stations that have become an industry best practice in parking lots and institutional campuses. Traditionally used as a means whereby an individual can summon help when in — or perceived to be in — a threatening situation, features have been added to these devices that allow them to be used to broadcast prerecorded or live messages. This approach would be most applicable in the institutional environment, where it could be expected that a significant portion of the population would be outside and within range of the broadcast message. One example of this is the Talk-a-Phone () WEBS (Wide Area Emergency Broadcast System) family of devices that provide both interior and exterior audible notification options that serve as either stand alone units or can be incorporated into their WEBS towers.
An extension of this is what is commonly referred to as Giant Voice systems, referring both to a specific product as well as a group of exterior products that provide live and prerecorded voice and tone messages over large areas. This particular family of mass notification solutions has seen early adoption in the DoD environment but is also experiencing increased use in the institutional and petrochemical sectors. Several manufacturers offer these types of systems, including HSS Engineering (giantvoice.com), Cooper Notification (coopernotification.com) and SimplexGrinnell (simplexgrinnell.com). All of these large-scale exterior systems can be integrated into enterprise solutions that address interior spaces and other forms of mass notification. Current technology routinely uses spread spectrum wireless communication between the system head-end and the exterior notification devices. Many product offerings now include interfaces to traffic and weather alert notification devices.
Care must be taken in the selection, design, and implementation of both interior and exterior amplified voice delivery mass notification systems to ensure the intelligibility of the signal. There are several techniques available to measure intelligibility, one being the objective instrument based Sound Transmission Index (STI) defined by the International Electrotechnical Commission (IEC) standard 60849. Most specifications for mass notification systems require intelligibility score greater than or equal to 0.70 on the Common Intelligibility Scale (CIS). General factors affecting intelligibility include signal-to-noise ratio (initial quality of signal), distance of the listener from the source, source directivity, reverberation due to varied device locations and sound reflections.