Achieving Clear Audio

Critical communications tools help keep staff, visitors and vendors safe.

• By Diane Ritchey
• Nov 19, 2025

In today’s ever-changing world of security and risk management, effective communication via an intercom and door entry communication system is a critical communication tool to keep a facility’s staff, visitors and vendors safe.

But how do you choose the best communication system for your facility? There are several considerations, such as where it will be placed, how it is built, whether it can be integrated with other security systems, and more. But there is one consideration that takes precedence over all of them: does it provide clear audio in every situation?

The primary function of an intercom system is voice communication. If the person on the other end cannot clearly hear, or you cannot clearly hear them, then the system fails at its most basic task. Clear audio allows security teams to detect tone, urgency, accent or emotion; identify speakers with confidence; confirm names, reasons for visits or security codes without repetition; and provide directions or reassurance that help is on the way.

Poor audio quality interferes with those goals and can lead to:

• Misunderstood instructions
• Delays in response time
• Frustrated users
• Increased security and safety risks

In some environments where quick decision-making is essential, unclear audio or muddled speech is not just inconvenient; it can be dangerous.

No one would buy a video surveillance camera if it did not provide video, or an access control system if it did not allow or permit entry, so why settle with bad and unclear audio with an intercom system? Here is how to achieve clear audio that allows users to hear, be heard, and be understood every time.

The Human Speech
Understanding the elements behind human speech is important to understand how to achieve clear audio.

Human speech consists of vowels and consonants. The vowels lie in the lower frequency range (around 250 Hz - 1,000 Hz) and the consonants lie at a higher frequency range (around 2-4kHz). While the vowels are important for the naturalness of speech, it is the consonants that are the bearers of information and that are extremely important to speech intelligibility.

Humans can detect sounds in a frequency range from about 20 Hz to 20 kHz, and the human ear is most sensitive around 2-5 kHz, so having a clear and non-distorted signal in that frequency range is very important for the understanding of speech (according to the Fletcher-Munson curve). This peak sensitivity is why speech, alarms and critical communication signals are designed to emphasize this range and why an intercom’s design should accommodate that frequency range.

External Factors
Once the elements of human speech are understood, it is then important to understand how external factors which can affect the intercom’s audio.

One element is the speaking habits of the intercom user. Some people speak louder or more intensely than others. And some users will stand close to the intercom, while others may stand further away.

If the incoming audio is not properly processed the speech quality at the receiving end will be reduced. Therefore, the intercom’s microphone sensitivity must automatically adjust to compensate for variations in the speaker’s intensity or and loudness as well as their distance from the microphone.

Another element is the ambient noise around the intercom and the user. To achieve superior speech intelligibility, an intercom must produce sufficient sound pressure above the prevailing noise levels. Noises that greatly impact audio quality at a building entrance include people speaking or yelling nearby, alarms, and noises from cars, buses, or trains, in addition to construction. Sounds such as wind or waves have a smaller impact.

Therefore, an intercom must be designed to deliver audio that is at least 10 dB louder than the ambient noise.

A third element is the quality of the audio received from the other side. That is why it is important that the intercom has a way to dynamically reduce the loudest parts of the message while amplifying the quietest ones to provide a consistent volume and allow for clear audio.

Features to Look For
Achieving superior audio requires intelligent software features that adapt to the nearby environment. They include acoustic echo cancellation, which means that the microphone will only respond to acoustic transmitted sound from the person speaking in front of the intercom and not pick up sound emitted by the intercom’s own loudspeaker and transmit it back to the other end.

When sound from the loudspeaker is picked up by the microphone, the Digital Signal Processor (DSP) recognizes it as feedback and removes it from the microphone signal, preserving only the actual speech from the speaker.

Automatic gain control automatically adjusts the microphone’s input gain to maintain a consistent audio level at the receiving end, regardless of how loudly or softly someone is speaking, or how far they are from the microphone.

For speech output to be intelligible on an intercom, it must be 10–15 dB above the ambient noise level. Automatic Volume Control (AVC) detects the noise level in the area and adjusts the loudspeaker volume in real time, to ensure that voices are clearly heard, even with background noise.

Active Noise Cancellation (ANC) algorithms continuously analyze ambient noise and subtract it from the microphone signal, ensuring that a clear speech signal is sent to the far end.

Dynamic Range Compression will reduce any large variations in the incoming audio between the loudest and softest areas. It results in a more consistent volume of speech signal and enhances intelligibility.

For the best audio quality, physical design also matters. An intercom speaker design should not include two overlapping stainless-steel plates, which will trap some of the sound waves between them and create distortion. Instead, the speaker grille should incorporate an anechoic, circular design where there is no reflection of sound waves as they pass through the station’s faceplate.

The exterior should also feature a solid aluminum, die-cast frame and an acoustically transparent poke screen so that someone cannot tamper with it.

Achieving Audio Clarity
Overall, it is meaningless to buy an intercom or communications system if the audible announcements and messages are muddy or unclear. Therefore, it is important to consider all the above features and elements, and to select a solution that provides audio and voice technology that allows people to hear, be heard and be understood, in every situation.

This article originally appeared in the November / December 2025 issue of Security Today.