So you got your recording done, all is dandy, until you discover cracks, pops and hums all over the piece! What to do? Don’t fear, if there is in one advantage that digital has over analog, it’s in the cleanness field.
The first thing that should be said is so utterly basic that you will think “what does he take me for? An idiot?”. I don’t take you for an idiot, but too many people just don’t take this basic fact into consideration.
If you record it well, there is little or no need for the things that I will talk about in this post.
So how do you do that? Well, first of all, you might want to keep the mic away from your noisy computer. You don’t think the hum is captured? It probably is, and when you boost the volume it might be a very annoying thing on top of that. Secondly you might want to keep your desk, or wherever your sitting, rather clean from unnecessary papers and other things that makes a sound if you happen to touch them. And don’t put your harmonica next to the fan!
Search and destroy
But accidents do happen, and sometimes they’re not that hard to fix either. If the noise is a loud click, pop or any other sudden sound with a high level, it usually isn’t hard to find. Just listen for it while looking at the waveform, it should be easy enough to spot it. If you use a proper audio editor (and you should!) then it most likely supports non-destructive editing. This means that you can cut all you want in the sound in your editor without harming the original file. Seek for the noise and go in and cut it out, alternatively lower the volume where the noise is.
Fade in, fade out
When cutting in a waveform this way you will want to be really precise to where you cut, other wise there is a risk that the cut in itself will produce a pop! So how do you figure out where to cut? Zoom in, really close and cut where the waveform is lined up as it was silent. Depending on how your audio editor displays waveforms it may look differently. It shouldn’t be a problem for you to figure out where the noise begins.
Clicks and pops occur from cutting when the ending section of the waveform is at a different place than the beginning. If it is impossible to make a cut like that (it can be hard if there’s several different sounds going on at the same time) you can use a fade out and a fade in if your editor supports it. This should be a very very short fade, barely not even audible, but because of this short fade the pop or click will disappear. Consult your audio editors manual for fades.
For information on dealing with more “colorful” noise, read the post “Dealing with noise”.