External microphones can be connected for higher-quality recording, or for achieving optimal microphone placement.
A camera is often mounted in the corner of the room near the ceiling, although this placement is not ideal for a microphone, since the hard surfaces of the ceiling and walls create reverberations and distortion in the sound. If possible, place the microphone away from large, flat surfaces.
Figure 3: A camera mounted in the corner of a room is not the best solution for audio. The red line shows how indirect sounds create delays and distortion, as compared to direct sound (blue line).
Sound propagating through the air is subject to attenuation, meaning that as distance increases, the intensity of the sound will gradually diminish. Doubling the distance will lead to a four-fold drop in sound intensity.
Figure 4: Moving the microphone away from other sources of noise – that is, closer to what you actually want to record – will have a big impact on the quality of your recorded sound