Setting up audio in video surveillance: Guidelines to follow

Audio plays a key role in video surveillance. It provides more context about a scene and can also serve as an effective deterrent to critical activities. To get optimal audio performance, getting the right equipment and setting up the system properly are essential.
 

Microphones

 
Equipment-wise, microphones are needed to pick up sounds. Today, microphones are built into most of the security cameras in the market and are quite useful in most scenarios. However, there are scenes or environments where the use of external mics is called for.
 
“Some of our cameras have an in-built microphone and from an installation perspective it can be convenient to use it. It could also lower the cost of the needed equipment and installation somewhat. However, in some cases the intended camera placement is not the optimal position for a microphone. Shorter distance to the source of the sound is better, and by using an external microphone, you get more flexibility in placement of the microphone and the camera,” said Carl Malmqvist, Regional Director, South Asia Pacific, and Dinesh Rai, Business Development Manager for Network Audio, Asia Pacific, at Axis Communications.
 
“For risk-critical, highly sensitive government and military buildings, as well as wide-area applications such as water treatment plants, refineries, and power generation facilities with challenging environmental conditions, including wind and high levels of background noise, it may be worthwhile to factor in the use of specialist microphones. These can operate effectively over long distances, making them ideal for monitoring large perimeters without requiring proximity to the source of the sound. They can pick up sounds at various frequencies and detect subtle noises, such as footsteps or even whispers, before perimeter breaches occur,” said Sean Um, GM and Head of European Business Development Team at IDIS.
 

Network speakers

 
Audio can also act as a deterrent. Once a suspicious individual is detected by the camera, the operator can play a message or simply “talk down” to the individual. This is typically done through a network speaker instead of the camera’s own speaker.
 
“For effective deterrence, especially in open or outdoor spaces, using a network-connected speaker is generally more reliable. While some manufacturers may include built-in speakers in their cameras, the output is typically limited in volume and clarity. A dedicated IP speaker, like Zenitel’s offerings, with sufficient power and coverage ensures that warning messages are heard and understood. It’s important to choose a speaker that integrates with the VMS or camera system, supports standard protocols, and is rated for the environment where it’s deployed,” said Adam Lowenstein, Product Director at i-PRO Americas.
 
According to Um, though, the market is expected to see more cameras with high-quality built-in speakers so users don’t have to get them separately.
 
“Adding speakers to a new surveillance system significantly increases initial costs and is often unnecessary for many typical surveillance applications. Over the last few years, security cameras have advanced to include low-light capabilities, eliminating the need to purchase additional lighting when upgrading surveillance systems. We predict a similar trend, albeit a slightly slower advancement, for built-in speakers,” he said. “Once there is more availability of cameras with in-built speakers, these will work seamlessly with the surveillance alert system, providing users with cost, configuration, and maintenance advantages to achieve a lower total cost of ownership.”
 

Proper setup

 
To get the best audio performance, installing the cameras and audio equipment properly is key. “For microphones on indoor security cameras, video coverage usually takes precedence. If there is a choice, and audio is prioritized, installers should avoid installing in inside corners where sounds and echoes are concentrated,” Lowenstein said. “Outdoor microphones should be placed in locations that avoids echoes, wind noise, or interference from machinery. Installers can conduct live sound tests to find a spot with the best signal-to-noise ratio. If using external microphones or speakers, proper shielding and mounting angles can make a big difference. Directional mics aimed at key entry points or high-risk areas are often the most effective. For broadcast, the IP speaker should be mounted where the target audience is likely to hear it, and it must be loud enough to cut through ambient noise.”
 
It’s important to note, though, that in a surveillance system, video capturing should still be prioritized over audio. “In most applications, the primary function of video cameras is to capture high-quality images; therefore, we advise against compromising on camera siting to improve audio capabilities. Instead, cameras should be positioned to capture the clearest field of view, without blind spots. If problems are encountered with audio, alternative methods should be used to rectify the issue, such as removing or muffling nearby noise sources where possible, or utilizing external microphones and speakers,” Um said.