Handbook for Sound Engineers

Intercoms 1565

Today there are smart security devices that incorpo-
rate the best features of both a listening device and a
noise trigger without many of the drawbacks.
One effective method is a sound sensing device that
continually adjusts itself to background noise levels,
while detecting and discerning the unique sound charac-
teristics of specific sound patterns usually associated
with crisis and emergency situations. When the system
picks up one of the crisis sound patterns it fires and
alerts security personnel of a probable emergency situa-
tion in a particular area. The system can also automati-
cally turn on video cameras, sound alarms, or activate
two-way intercoms, so that security personnel can

instantaneously communicate with individuals involved

at the scene.

Because this type of system continually adjusted

itself to the continuous changes in levels and frequency

response of background sounds, and has the ability to

insert a time gate to further assist in doing away with

false alarms, it is able to isolate the sound of a scream or

the smashing of a pane of glass, Fig. 43-7.

This type of monitoring is useful in security applica-

tions including correctional facilities and mass transit

subway authorities, parking lots, schools, large ware-

houses, and empty office building hallways after regular

business hours.

Figure 43-6. Basic building communication system. Courtesy Ring Communications, Inc.

60

Speaker Speaker Speaker

60 60

CAR 1A BK

CAR 4A BK

Door 1A

Freight

0002 17:16:24

114

114

125

122

Machine

room

Machine

room

Machine

room

Car 1 Car 2 Car 3

Telephone

interface

Central

office

Lobby/Security desk Building Manager

Telephone

Master

Elevator communications system

with off premise dialling and

A.D.A. compliant