The importance of intelligible audio in security
- By Dan Rothrock
- Aug 02, 2021
Sounds are a part of our everyday lives. They come
at the right time, and at the wrong time. Many
sounds we hear are appreciated, such as a bird
singing, children laughing, or your feet crunching
in the snow as you walk.
Scientifically, sounds are vibrations in the air (or in the
water) that we pick up with our ears. The bigger the waves (the
amplitude), the stronger the vibrations, and the louder the sound
is for us to hear.
In security and safety, audio and sound provide valuable
information that has inherent value across many applications and
But what if the sound is distorted, or you can’t hear the sound
clearly, due to background noise? Many security enterprises face
that challenge. Facilities such as school campuses, hospitals, and
manufacturing facilities, for example, will employ intercom and
audio solutions to help their security teams to mitigate risk, to
only find that audible announcements and messages that are
being delivered can’t be clearly heard or clearly understood.
For example, here’s a situation with which we are all familiar:
you are entering a parking garage and you can’t hear what the
security guard says because the noise from the vehicle behind
you is very loud. The background noise is very present, and it
interferes with your ability to speak to and hear the security
guard, and the guard’s ability to hear you. What security risks
are not being identified when you can only see someone, but you
cannot hear them?
AN AUDIO SCORECARD
And therein lies the challenge: background noise that cannot
be overcome and sub-par audio quality, and many security
teams may just accept it. Many security teams may believe that
their solution is the best that is available, and no other solution
can perform better. But it doesn’t have to be that way. What if
unwanted noise could be suppressed; wouldn’t that make it a lot
Wouldn’t that also mean you are getting the value and ROI
from your security investment and that you are mitigating risks,
which is what your security technology is supposed to help you
There are solutions that are intelligible in even the most
challenging circumstances that enable security teams to deliver
clear instructions with intelligible voice and audio whenever the
need arises. These solutions make it easy to hear and understand,
through technology that listens and detects the background noise
and filters it out. This feature vastly improves the quality of
assistance provided by security guards and control rooms.
Does your current intercom solution have what it takes to
provide clear, intelligible audio? We suggest that you measure it by
using an Intelligibility Scorecard that we have found being used
by the most knowledgeable thought leaders in audio. Try using
it to help you evaluate your critical communication solutions.
When looking at how your intercom solution performs (or does
not), make sure that the solution employs:
Acoustic echo cancellation. Prevents feedback and enables clear
and hands-free communication, even at high volumes (95dB).
Automatic gain control. A voice that is too loud or too weak
(too close or too far) will be leveled out to an undistorted and
Anechoic speaker design. Prevent distortion from “standing
waves,” which is the combination of two waves that are moving
in opposite directions. Standing waves are formed when a wave
bounces back and forth in a situation that produces constructive
A rigid stable frame. Microphone damping to isolate
microphones from vibrations at loud volumes.
Acoustically transparent poke screen. A feature that makes
the speaker vandal resistant while maintaining the quality of the
THE SUM OF THE PARTS
Yet, it’s also important to move beyond considering those
elements as “features.” Think of them as the holistic criteria
for evaluating your audio and voice solutions to meet your risk
Together, it is literally the difference between bad audio and good
audio. Those features that remove the noise surrounding the intercom
means that inside the station, the microphone signal is automatically
being measured and is calculating the noise components in that
signal. That process effectively removes noise components, leaving
a clean speech signal even if the original speech level is below the
level of the surrounding noise. The result is a clear Open Duplex
conversation, even with a passing train in the background or talking
from inside a car while stuck in front of a barrier.
Another major advantage of audio systems, whether they are
called access control points at the perimeter, IP Audio, elevator
systems, telecommunications solutions or intercom, is when
physical and cybersecurity by design is employed in the product
design and manufacturing process. You move from a featurebased
strategy to a critical solution-based approach.
We have interviewed many security
managers who deployed based on price and
features and have not focused on intelligent
risk-based audio design. It’s time to change
This article originally appeared in the July / August 2021 issue of Security Today.