Q: Why should my customer add audio to a video security system? Most security microphones have an omnidirectional pickup pattern, so they can provide a larger coverage area. Some security microphones are built for specialty applications like vandal resistance or weather resistance; others are general-purpose. The range of AAC can go as high as 20 kHz, which lets you hear sounds beyond speech frequencies. Even if a security camera has a built-in mic, there are two reasons to think about using an external mic – placement and clarity.