Listen Clearly

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 situations.

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 easier?

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 to do?

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 clear signal.

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 interference.

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 audio.

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 mitigation needs.

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 that thinking.

This article originally appeared in the July / August 2021 issue of Security Today.