Audacity is a free, Mac/Windows/Linux audio editor. It does a great job cleaning up bad audio sounds in a relatively straightforward manner. It’s certainly worth having around and knowing a few tricks with it. And it can help your media projects sound better. Here’s how.
Mission one! Audacity is available from http://audacity.sourceforge.net. Mission two! (following the Beyonce theme here), get the MP3 plug in. There’s no need to waste hard drive space exporting to .wav when you can use MP3. For Windows or Mac OS X, follow the instructions on the Audacity web site to get something called the LAME library file and enable Export To MP3. For Linux users, you’re just a lucky little ducky. Our sister site FOSSwire has the skinny on installing it for Linux.
Now that you’ve got that, we can check out the workflow.
Step 1 is importing the video and audio from your camera on to your computer. This is one part that I expect you to know how to accomplish. In Numero 2, we separate the audio track from the import. In iMovie ’06, it’s Extract Audio. In Premiere 6.5, it’s right-mouse click Save Audio As. You figure this one out, too.
Step 3 shows us the extracted audio, and we open Audacity in Step 4 and choose File >> Open to bring this Exported clip in to the program. Here we do the magic to clean it up, then again File >> Export Audio As MP3 and we see in Step 5 that we have our new, cleaner file. In Step 6, we import this back into our video editor! Not shown are the final steps where, due to our low-budget editing prowess, we eventually land that lucrative Hollywood contract.
Okay, so let’s do this crazy thing. We’re going to focus on Step 4, the magic part.
One of the first things we can do is eliminate some background hiss. This almost always makes it sound better, and it’s a two step process. First, find some section of hiss with no other sound. Some audio guys take a few seconds to ‘establish the background sounds of a scene‘ before telling the director they’re ready. Feh. Primadonnas.
Once you find this golden nugget of audio, use the mouse and highlight it. This is going to establish the baseline for the audio you want to remove.
Next, choose Effect >> Noise Removal and click the Get Noise Profile button. Don’t worry if nothing happens; no one saw the car in those old Infinity commercials, either. The, highlight the part (or parts) of the track where there’s audio you do want to capture. Go back to Effect >> Noise Removal, only this time move the slider all the way to the left. Click Remove Noise, then go back and listen to the track.
If you hear something like Transformers sounds or pops and creaks, then you probably removed too much noise. Go back (Edit >> Undo) and try another section for your â€œGet Noise Profileâ€ selection, and see what you can come up with.
The next step is easier; highlight the silence you’d used for the profile, and choose Generate >> Silence. You’ll be asked how much; just click OK. This replaces the hissy sound with pure silence, and is the preferred way to handle this in Audacity.
There’s two more effects you can try out here: normalize and compression. Normalizing makes the quiet parts louder, and the louder parts quieter. Compressing a track tries to get rid of the highest of highs and the lowest of lows, making the audio more in the sweet spot for a wide variety of equipment. Highlight the various sections, choose Effect >> Normalize or Compression, and check the results. I usually get pretty good results sticking with the defaults, but you might get lucky mucking around. Try, try, try, with your trusty Edit >> Undo close at hand.
Once you’re done, export the file and name it something different to indicate that this is an improved version of the audio you exported FROM the video editing program. Then you’re ready to bring it on in and line it up.
I suggest leaving them both in for a few minutes; mute one and play the other, then reverse. Compare as to whether you actually made it better. If so, delete the original and keep your mod. If not? Git back on the horse and try it again. Happy filming.