Audio in Video Surveillance: From Common Mistakes to Professional Sound
When people talk about video surveillance, most immediately think about the picture — resolution, night vision, field of view. Yet experience shows: video without quality audio is only half the story. In many cases, it’s the audio that becomes the key piece of evidence, capturing what the camera can’t see. But achieving good sound in surveillance systems is far more complex than it may seem.
Why Does Audio Often Fail?
The main reason is lack of attention to detail. Many users mount microphones “where it’s convenient” or simply rely on the built-in mic of the camera, only to end up with hum, echo, and background noise that make the recording painful to listen to. Another common mistake is using outdated or overly compressed codecs. The result is audio that sounds like a landline call from the 1990s.
The good news: there are proven rules that can help avoid these pitfalls.
A Checklist for Quality Audio in Surveillance
1. Forget the G7… Codecs
G.711, G.722, G.729 and their relatives are fine for VoIP telephony, but not for surveillance. They severely limit frequency range and clarity, producing “voice in a tin can.” For proper audio, choose codecs with a sampling rate of at least 48 kHz and a bitrate from 128 kbps.
2. Never Mount Microphones on Ceilings or in Corners
This rookie mistake guarantees disaster. Ceilings and corners collect all background noise: footsteps, ventilation, echo. The result is muffled, unintelligible speech.
3. The Sweet Spot Is 1.5 Meters
At this height, the human voice is captured most naturally and clearly. Mounting higher or lower leads to distortion.
4. Use Cameras and Recorders with Proper Audio Support
IP cameras deliver superior sound because they allow flexible adjustment of parameters: sampling rate, bitrate, and codec type. In this case, the hardware truly matters.
5. Quality Power Supplies Are Not Optional
A cheap power adapter can introduce hum, buzz, or interference into the audio signal. For professional results, only reliable power sources will do.
6. Use Only Microphone Cable
Audio should never be run through “whatever cable is lying around.” Proper shielded microphone cable is essential to block electrical interference — especially when installed near power lines.
7. Invest in a Good Microphone
Don’t cut corners here. Cheap microphones pick up everything but speech. A high-quality microphone ensures clarity, intelligibility, and credibility in recordings.
Audio as Evidence
Video surveillance is no longer just about “eyes.” In courtrooms and investigations, audio recordings often carry even more weight than video. Threats, admissions, or simply the tone of a conversation can provide decisive proof. But for audio to stand as evidence, it must be both clear and technically sound.
The Bottom Line
High-quality audio in video surveillance is not an “extra.” It’s a vital part of the system. Following a few simple rules — from choosing the right codec to mounting microphones at the right height — turns your recordings from useless noise into reliable information.
So when asking, “Do I really need audio in video surveillance?”, remember this: without it, your system is only doing half the job.