Over the weekend I listened to a lot of podcasts. I noticed that a lot of the “amateur-recorded” podcasts don’t use any compression. For instance, one of my favorite podcasts, Smodcast, seems to have just started using a compressor. The old Smodcasts were really bad for having one of them yell into a mic and blow my eardrums away, and then in the next instant be too quiet to hear, making me turn it back up again just to have someone yell in my ear again.
Podcasters, please use a compressor, and I’ll explain how… briefly. Compression was probably the single hardest thing for me to learn when I started recording. Recordists on forums where I’d post samples of my recordings would say things like “whoa your compressor is breathing…” or “dude, that’s completely smashed..” and I didn’t have a clue what they were talking about. If you want to hear a compressor breathe, listen to Smodcast 113. I’ll explain why a compressor breathes…hopefully in a way podcasters can use.
Simply, compressors reduce the loud parts so that the quiet parts, when turned up, are louder, reducing the dynamic range of the audio. Think about a modern rock song, it’s probably completely smashed so that there are absolutely no quiet parts and everything is equally loud. Now contrast that in your mind with a movie, where the whispers are almost inaudible and your neighbors can hear the explosions and gunfire. Now you understand the basics of a compressor… all compressors are generally the same, once you learn what your particular compressor is doing – you can actually hear the difference. Until then, if you’re like me, you’ll slide the sliders around and think “I don’t hear what this is doing, but I’m supposed to use it”.
So when compressors breathe, they “let go” and the audio expands back to it’s original state. Expanding is the opposite of a compressor, and can be used to eliminate background noise by expanding the audio and then gating off the undesired noise (like a background hum or buzz). If you look at your particular compressor’s settings (in whatever audio production tool you’re using), you should see an attack and release function (I use renaissance compressor by Waves, or RenComp). When a compressor releases, the original audio is fully dynamic again – everything is loud and full and you can hear cars driving by outside the podcast window. When someone yells into the mic again, the compressor engages for however many seconds is on that release function, over and over, and it sounds like the audio is breathing. (You hear the hiss of background noise, then it engages and you don’t – because the yelling is the only thing that exists inside the compressed audio – over and over, and it’ll sound like hiss-breath.)
To keep your podcast from breathing and even engaging too late, turn your attack really low and your release really long, or even permanent, if it allows. RenComp has an automatic release control called ARC (pictured). Attack is used mainly for music, where you want the transients, the initial smash of a drum beat or pick of a chord, to come through uncompressed and then engage and compress the rest. For podcasting, just smash it all to 3.5 – 5.0 db. Then turn it up to compensate for the reduction in loudness. You have to turn it back up, because the compressor just reduced the loudest parts by the amount of compression you just set (3.5 db for instance), making the quieter parts equally as loud as the loudest parts (i.e. excited Kevin Smith yelling into the mic is just as loud as Scott Mosier).
When setting your compressor, pull the threshold level down into your audio; this is what the compressor will engage upon. Sometimes a compressor will show the “knee” instead of the RenComp’s level meter, but it’s essentially the same thing, just pull the knee down into the jumping audio meter.
So please, if you are on the production end of a podcast out there, please use some compression for my ear’s sake as well as my speaker’s sake! I’m likely to crash my car turning it up and down!
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