Sound volume falls off rapidly as you move away from a sound source. The first thing to try is moving the microphone closer to the source of the sound that you want to record.
Next, (if your camcorder has manual audio control) turn up the audio recording level, or, if you are shooting interviews for a documentary, you can switch to AGC (automatic gain control.) Modern camcorder AGC’s are usually suitable for documentary interviews, but they can have unwanted tendencies to boost their gain during silence, so this should be avoided when shooting narrative films.
If neither of these things works, try using a different microphone.
Dealing with background noise
Your first option when dealing with background noise is to eliminate the noise sources. This may be as simple as turning off an air conditioner or a refrigerator during filming.
(Note: If you turn off a refrigerator, tape a sign to the refrigerator door saying “TURN ME BACK ON AFTER THE SHOOT.”)
You might also try to reduce background noise by hanging sound blankets – asborbant blankets or cushions that are designed to deflect and absorb background noise (these are especially useful for removing reberberation).
Although you can remove some noises with sound editing software, many noises (like refrigerators and traffic noise) are impossible to remove (at least, without removing part of the audio you want to retain).
If you can’t eliminate the noise source or hang sound blankets, change locations.
The slightest breeze or movement of air can cause wind noise as air moves over a microphone. Wind noise can be a problem inside as well as outside. Air movement within the room where you are recording may be enough to cause this noise.
You should assume that you need a windscreen all the time. There are windscreens for every type of microphone, including in-camera microphones. The directional microphone shown below is covered with a Rycote Softie windscreen.
Wind noise is nearly impossible to remove from a recording after the fact.
Reverberation happens when sound bounces off hard surfaces. If you are recording in a location with reverberation your only solution is to hang something soft like sound blankets on the walls.
You cannot remove reverberation from a recording with sound editing software.
Change locations if you cannot remove the reverberation.
