Now that is very much over-simplified and yet it is _so_ true! The poorest audio that you and I have heard in our friends videos are likely because their microphone (usually mounted on the camera) was far away from the actual sound source, whether it was a group of children performing on stage, a guest speaker, or an interview... if your microphone is any distance away from the subject there is a great potential for distracting audio.
And then there is the fact that as your microphone is further away from the subject there are likely other sound sources that will work their way into the microphone... and if those sources are closer to your microphone those sounds will come in louder! So the person talking near your camera, the air-conditioner, the person moving their chair a few feet away will provide sounds louder than that precious child's voice you _want_ to hear clearly!
So - to remedy this problem, we want to get our microphone up close to the subject. Using either a wireless microphone or even a wired microphone that connects to your mic (microphone) input on your camera that you can place near the subject will provide you with greatly enhanced sound quality! In future posts I will share thoughts and info on different kinds of microphones and where to best place them.
This external microphone capability is so important - that is one of the things I advise my friends to look for when shopping for a new camcorder, make certain it has a mic input!
Now, one last suggestion for today - when you plug in an external mic, it defeats or turns off the internal mic. So if you mic plug is not all the way in, you may have a silent movie. To ensure your microphone is working and picking up the audio you desire - it is important to wear something to hear (or monitor) the audio.
A pair of headphones or an even ear-buds will enable you to confirm this (if it's a loud performance venue, you may appreciate a good pair of muff earphones... but then maybe I can be accused of being a little 'old-school' here. So yet another important feature to look for when shopping for a new camcorder - a headphone jack!