An Integrator’s Guide to Adding Audio to Surveillance Systems

As a systems integrator, chances are, you have probably completed dozens, hundreds, or even thousands of video surveillance installations. You know exactly what to do when your customer needs video system or wants to expand their system. But what do you do when your client asks you to add audio to a security camera?

Today, more end users are wanting to deploy audio for alarm verification, dispute resolution, visitor management, remote monitoring, quality assurance, employee training, business intelligence and more. Video only tells part of the story. Sound provides critical evidence to understanding not just what took place, but also why something happened as well as underlying motives. Audio provides the missing puzzle piece, and this is why it is seeing strong adoption.

When it comes to adding audio to an existing surveillance system, there are two options. The first is to use cameras with built-in audio. The second is to choose an external microphone. The challenge with the first option is that cameras often do not yield optimal audio recordings as the microphone is placed inside the camera versus being mounted in an area of the room that is best suited for sound pickup. If your customer requires high-quality audio where recordings could be used in investigations or court procedures, you should opt for an external microphone. 

While integrating external microphones with cameras is simple, there are several factors to consider. Here is a step-by-step guide to get you started. 

1. Know Your State Regulations: Audio monitoring is permitted as long as there is either no expectation of privacy, such as in a public place or when consent has been given. Each state has a different policy as far as what constitutes consent – it’s either one party or all parties involved. Refer to our Audio and the Law map for more information or check with your local attorney for any specific concerns.
   
2. Define Your Audio Needs: Is your customer solely looking to capture audio from the surveilled scene? Or, does a security officer in a control room need the ability to talk back or talk simultaneously with someone on the ground? These questions will determine whether you should choose a simplex microphone (where audio is sent in one direction), half duplex microphone (where audio is sent in both directions, but one at a time), or full duplex microphone (where audio is sent in both directions at the same time).
   
3. Determine Line Level or Mic Level: Microphones give off two different types of voltage: line level output and mic level output. A mic level output is often in the range of ten-thousandths of a volt while line level output is about one volt. Typically, line level microphones are the most deployed options as the audio signal is amplified (and thus stronger) and features reduced gain for lower ambient noise and better sound clarity. Most network cameras also support line level input. Either way, make sure to select a microphone that has an output level that matches the camera’s input level.  
   
4. Select the Right Form Factor and Features: Consider where the microphone will be placed. Do you plan to mount the microphone on the ceiling? Is the ceiling standard height or is it a high ceiling that may require the microphone element to hang closer to the ground? Is the microphone being deployed in an environment at risk of tampering where vandal resistant housing will be key? Will there be a lot of background noise where you need a microphone that reduces ambient sounds? Think about these answers and they will help you select which external microphone and form factor will perform best in your deployment. 
   
5. Define your Power and Audio Playback Source: If you are deploying line level output microphones, you’ll need a power source. Consider using an audio base station, which not only powers the microphones but also provides audio playback features as well as the ability to interface with video system or NVRs. You can also simplify this process by selecting a microphone that automatically comes with a base station.
   
6. Plan Your Audio Configuration:  One of the most common options is to connect the microphones directly into the cameras in a plug-and-play setup. This is fairly simple and involves running the microphone cabling alongside the camera cables. Then, make sure you select the correct audio settings on the camera itself such as turning “on” the audio level or adjusting the bitrate, gain, etc. If you choose a digital microphone that connects directly to an Ethernet port, connect a CAT5/6 to a RJ45 jack. Locate device name and IP address using the discovery tool. Then, go online and set a username, password, and other audio settings for your digital microphone. Lastly, select “live view.” If you want to connect the microphones directly to a NVR or NVR, apply 12Vdc to the microphone. Then, connect the microphone directly to the audio in the storage device. Lastly, make sure you select the correct audio settings on the NVR/NVR such as “line in” bitrate, gain, etc.
   
7. Set Up Your VMS: First, ensure that the video management software your customer is using supports the type of audio functionality, such as bidirectional audio, that your customer is looking for. Next, tailor the audio settings in your VMS. For example, though a microphone may be plugged into one camera, through the VMS, you can associate it with multiple cameras. This allows video and audio from a scene to play no matter which camera the operator is viewing. 
   
8. Test the System: With everything set up, conduct some tests. Evaluate the audio pickup. Make adjustments where needed. 
   
9. Install Signage: Lastly, whenever you deploy audio surveillance, always install signage that says “Audio Monitoring on these Premises” to ensure the expectation of privacy is removed.