A camera microphone captures audio alongside video, either built in or wired to a camera’s audio input. Audio adds context to an event, but recording conversations carries legal and privacy duties that vary by jurisdiction, and an outdoor microphone mostly picks up wind, traffic and noise from its own housing.
Audio is the feature most often enabled by default and least often thought through. It can make a clip far more useful, and it can also create obligations that a silent camera did not.
Audio in and out
A camera with an audio input needs a microphone of the right signal type and power, usually a powered or pre-amplified unit for anything beyond a few meters. The recorder then has to store audio for that channel, and the viewer has to be able to play it back.
Legal and practical limits
Consent rules for recording conversations vary by state and by setting, and they are a legal question rather than a product feature. Practically, an outdoor microphone is exposed to wind and traffic noise, so a wind muff and careful placement matter as much as microphone quality.