Audio Combines Communication And Security
High-quality sound systems can be implemented over a virtually limitless, multi-zone area
- By John T. Wiggins
- Jul 01, 2012
Over the past two decades, many widely known incidents have occurred
that have caused the loss of life. Emergency situations,
ranging from the 9/11 attacks to fires to public stampedes at
sports and religious gatherings, have caused various agencies to
begin to analyze the weaknesses of all types of communications
systems used in venues and transportation hubs worldwide.
Historically, such systems were focused primarily on fire alarm communications,
but in relatively short order, the requirements have expanded into all areas
of life safety and emergency communications.
Increasingly, these systems must comply with local, national or international
codes and standards. In the United States, we typically see National Fire Alarm
and Signaling code NFPA 72, and internationally we are beginning to see countryharmonized
standards like EN54. Before the harmonized agreement, each European
country had its own equipment standards. NFPA 72 has been revised many
times, and in 2007 a definition for mass notification systems (MNS) was added.
The Emergency Voice Alarm Communication System (EVACS) standard was
written in 1985, but intelligible voice sound—not the old whistles, bells and tone
signalling—was not included until 1999.
In regard to intelligibility, arguments have raged from all factions in the alarm
and communications industry ever since NFPA mentioned the word. Intelligibility
is not easy to quantify; it is a science requiring complex measurements.
However, if people in an emergency cannot accurately understand the messaging during a crisis, how are they, en masse, going to save themselves?
To improve public safety, NFPA is attempting to provide guidance through
voice communication systems.
It is the responsibility of the authority having jurisdiction (AHJ) to determine
which spaces or areas require intelligible sound. Typically, AHJs don’t require intelligible
voice communications in closets, mechanical rooms, kitchens and the like.
However, it is unreasonable to expect the AHJ, typically a fire marshal, to understand
the complexity of acoustical testing and interpretation of data required to
determine if a system provides a good speech transmission index (STI) or a poor
one. It requires an individual with the proper academic background and audio experience
to measure and provide the STI data and the interpretation of the results.
If a region adopts NFPA codes, the AHJ is the person who determines if the
installation, performance, reporting and supervision of the system meet all the
required minimum performance specifications. The AHJ must certify the results in
order for the building to receive a certificate of occupancy.
The EU standard EN54—which is not a law—is a product-standard requirement.
EN54-16 permits the use of a voice alarm system for non-fire alarm purposes.
This allows the system to provide messaging in a wide range of emergency events,
such as a bomb threat.
EN54-24 details how a loudspeaker must be tested to verify the manufacturer’s
specifications, including sensitivity, power handling, frequency response and environmental
durability. EN54-24 also includes details regarding loudspeakers that
must be operated with their dedicated or included active electronics.
Sound systems that are used to improve transportation security have the ability
to improve the protection of people and property. These versatile and powerful
systems can reduce the loss of life associated with risks such as natural, technological
and man-made disasters. In addition, many of these systems can double
their usefulness by providing recorded entertainment when they are not required
to be a link in emergency communications.
Excellent sound reproduction is often distributed throughout sports venues, office
buildings, theme parks, entertainment venues, shopping malls and waterfront
gathering places. In the transportation sector, we see these specialized, high-intelligibility
loudspeakers used in airports, train stations, rail hubs, highway inspection
areas and marine applications such as ports, ferry terminals and aboard ships.
With the adoption of IP networks, typically via fiber-optical infrastructures,
advanced, bidirectional audio/video communication systems can be implemented
that are fully integrated with multiple points of control. No longer is it necessary
to be stuck in a central equipment room to control vast systems.
High-quality audio and video can be implemented over a virtually limitless,
multi-zone area. Networking allows the system to be linked over small or vast
areas with high redundancy, high reliability and freedom from any interference.
Sound projection patterns from loudspeakers may be actively or passively controlled
with a precision that would have been hard to imagine just a few years ago.
Let us look at some of the ways that loudspeakers are used to protect passengers,
workers and property against security threats, while providing communications for
- In Minneapolis, high-directivity, multiway horn loudspeakers are concealed
within attractive decorative housings to provide clear announcements as well as
emergency communications for a typically reverberant airport atrium.
- At London Luton Airport in the United Kingdom, a complex multipoint
control, multi-zone system delivers both paging and life safety. It ensures the
smooth operation of the airport for approximately 10 million passengers annually while providing for their safety
should the need arise. Loudspeakers
are zoned and distributed throughout
the facility, from its cathedralsized
shopping malls to the long
walkways to the gates. In each zone,
the loudspeakers have been carefully
selected for their power, coverage
and ability to deliver high-intelligibility
voice to every public area.
- In Orlando, the Orange County
Convention Center has installed
both fire alarm and public address
loudspeakers. In the event of an
emergency, the fire alarm enunciators
work first with automatic messaging.
The message is then repeated
on the public address system, which
is far more intelligible.
- In Venice, Italy, an audio solution
has been devised to keep the whole
city moving. Its tidal waterways on
a daily basis re-map the routes accessible
by waterborne taxis, buses
and service vessels and, on what is
usually dry land, by pedestrians.
To provide advance information of
water levels to the city, loudspeakers are located in 15 bell towers in
central Venice and in 15 other locations
on outlying islands. These
loudspeakers play musical tones,
which are now familiar to residents,
and inform them of tidal levels so
that they can plan to use routes that
will be accessible. Venice was a custom
project for the city planners,
system designers, installers and
the loudspeaker manufacturer, but
it remains a great example of how
well-implemented audio can solve a
problem for an entire city.
- In Seattle, train platforms use powerful
loudspeakers that have been coated
to make them graffiti resistant. Although
railway stations are wellknown
as highly reverberant spaces,
intelligibility can be maintained
by using multiple close-proximity
loudspeakers with well-controlled
coverage, directing the sound to the
people and avoiding highly reflective
- At Biga/Canakkale in the northeast
coast of Turkey, IÇDAS port has
two piers and a wharf with a total
in-port berthing capacity of up to
20 vessels at the same time. Controlling
ship movements is critical
and complex, and the sea port is
acoustically covered by a combined
shore-to-ship control and safety
warning system. Pole-mounted,
loudspeakers provide the high
sound levels needed with uncompromised
ship movements in the port to be
controlled by verbal commands.
- In Vancouver, British Columbia, an
auto/truck ferry terminal loading
area is acoustically covered with a
very high-power voice loudspeaker
system to provide instructions to
vehicles—even if their engines are
idling and their windows are closed.
- At the Capitol in Washington,
D.C., a roof-mounted public address
perimeter system is installed
that inherently has the control and
power to be used for evacuation if
required. The system provides intelligible
voice well beyond a 1,000-
- Denmark, which has a relatively
small population of 6 million, has
installed a giant emergency management
system. Nearly every person
across the country is within earshot
of the system’s acoustical coverage
and messaging. The system was
codeveloped by a partnership between
American and Danish firms.
Ten thousand sites throughout the
populated areas of the country ensure
even sound coverage.
It may be that the Danes are showing
the direction for the future of large-area
wide-acoustical security systems. These
systems, in conjunction with digital signage,
video surveillance, network control,
cellphone messaging and intelligent
analytics, can help in the battle to minimize
This article originally appeared in the Security Products Magazine - July 2012 issue of Security Today.