The security technology landscape is dominated by cameras, but in recent years, many security professionals have realized that video alone only gives half the picture. Despite advancements in camera resolution, analytics, and AI, without audio, critical context such as verbal threats, raised voices, or the sounds of breaking glass will go unnoticed.
As demand for adding microphones continues to grow, many integrators are looking at audio for the first time, and they often face a new set of questions when audio enters the mix.
Many of the same questions are frequently asked by integrators new to installing audio systems. Whether you are writing a proposal or planning an audio install, these FAQs and answers will help get you started building smarter, more complete security systems.
Q: Why should my customer add audio to a video security system?
The short answer is that audio fills in the blanks. Video captures what is happening; audio helps explain why. It adds a layer of context that can verify alarms, prioritize responses, support investigations, and even prevent incidents before they escalate.
In customer service settings, audio can clarify a disputed transaction. In educational and healthcare environments, it can provide documentation that supports training or compliance. In law enforcement investigations, only audio can hear a confession.
Audio provides different information from video. That’s why it’s already standard in other industries like consumer electronics, entertainment, conferencing platforms, and more.
Q: What type of microphone should be used for security applications?
Not all mics are created equal. Just as different types of cameras are more suitable for certain applications, the same is true of microphones. Most security microphones have an omnidirectional pickup pattern, so they can provide a larger coverage area. After all, incidents don’t always happen in the same place.
Different models of microphones can also have different levels of signal strength. Make sure the microphone’s signal level matches the input type on the camera. The most universal type is line level. You’ll see camera specs list this as “line” or “line input” when referencing audio compatibility.
Some security microphones are built for specialty applications like vandal resistance or weather resistance; others are general-purpose. The right mic for your application will often depend on the type of location it will be installed in.
Q: How should I handle cabling and power for microphones?
Most issues with microphone performance stem from cabling issues, so it is important to use the right cable and make sure the connections are secure. Equally critical is to avoid high-voltage wiring or fluorescent lights near audio cables. For best results, use 18/2 shielded or 22/2 shielded cable to connect a mic to a camera. The shielding is more important than the gauge. The use of a drain wire is recommended to further protect the mic signal from interference.
Line-level microphones require 12VDC power. A mic level (non-amplified) microphone doesn’t need external power. The tradeoff is that a line-level signal can travel much farther and is less susceptible to interference than a mic-level microphone.
Some devices split 12V power off from the camera’s PoE cable while still powering the camera. These allow for 12V availability in PoE-only installations.
Q: My customer’s camera already has options for audio compression. What’s the difference?
Compression tools get rid of sounds at very high and very low frequencies. These are mostly sounds that are beyond the range of hearing. Removing them allows the stream to be smaller without losing the sounds we would hear on our own.
Most cameras offer compression options using G.711 and AAC. Some cameras offer additional options, but these two are the most common.
G.711 is a compression standard based on telephony. It compresses to a range that closely resembles human speech (300Hz to 3.4KHz). The range of AAC can go as high as 20 kHz, which lets you hear sounds beyond speech frequencies. This can be helpful in security applications for hearing sounds like alarms or breaking glass. Most online audio streaming is AAC.
If your customer’s objective with audio is to pick up intelligible speech, then G.711 is suitable. If they want to have more environmental context of an area, then AAC will provide more information.
Q: My customer’s camera has an internal mic, so why would I need an external one?
Even if a security camera has a built-in mic, there are two reasons to think about using an external mic – placement and clarity.
Cameras are often installed in the corner of a room to provide a wider field of view. While ideal from a video perspective, it is hard to imagine a worse location for a mic. The camera’s placement means the mic is farther away from the sounds it is trying to hear. Because sound waves lose intensity the farther they have to travel, the sound that does reach the built-in mic will be quieter. Even worse, when a sound wave reaches a corner, it will reflect off the walls and ceiling, which creates echoes and reverberation. All of these factors make it more difficult to clearly hear sounds.
An external microphone placed closer to the source will pick up stronger sound waves. Generally, external mics are installed in the center of a room, and because sounds picked up by the external mic don’t reflect off corners, echoes and reverb are avoided.
