Hello, all! We’ve had so much news over the Summer and most of Fall that I’ve had to cut my own column to make sure we could fit it all in. But I’m back now, hopefully on a regular basis. I was going to pick up where I had last left off, but then I realized I left this particular series hanging last year before I was out with my broken leg. So I thought a refresher was needed to lead into the next article. It’s nice to be missed, so thank you all for your concern!

Our topic this time is compression. Not the kind you think of when you think about, let’s say, making an MP3 or something – that’s data compression. The compression we’re going to discuss involves dynamic range reduction. As with other technical topics in the past, I’m not getting into the mathematics or anything here - I’ll try to break it down as much as possible.
The main reason I wanted to address compression is to answer the question I’m getting more and more – “Why doesn’t my music sound right on the radio?” Well, is it sounding muddy or distorted? Hypercompression is the reason.

Let’s get some basic definitions out of the way.

Dynamic range is an audio term that refers to the range between the softest and loudest levels a source can produce without distortion. Put more simply, it is the difference in signal level between the loudest and quietest parts of a song or other audio source material, expressed in decibels. The reduction of dynamic range is known as audio compression.

The human ear, believe it or not, has a built-in compression system. When we hear something very loud, we can’t hear something quiet for a while because the threshold of our hearing has been raised.

How about a couple of examples? Okay. How about when you’re listening to a CD you bought at a store and all the songs are the same relative volume, meaning you don’t have to turn the volume up and down for each song? Or, for those of you who’ve recorded before, in a session the singer may be moving toward and away from the mic, and a little compression will even out the volume changes that would otherwise be recorded.
Something a lot of people don’t know is that radio stations (and TV stations, for that matter) use compressors, too. They’re required by the federal government to limit how loud they are broadcasting. This is why you don’t usually surf the FM airwaves and get blown away by some stations while not being able to hear others.

Now, if you’re compressing the ever-living-you-know-what out of your recording before taking it to the radio station, they’re compressing it even more and the result is not really what you’d want to call pleasant.

In about 1999, major labels started coming out with louder and louder CD’s. One reason tossed around was so their CD would jump out at the listener in a music store or in the consumer’s own home stereo CD changer. I don’t think anyone ever really found out the real reason, but it makes no difference now because the damage is done, so to speak. ALL CD’s are really loud now, so everyone else is just trying to keep up.

So, if the major label CD’s are so compressed, why does their stuff still sound good on the radio? Because, more often than not, the label has made special mixes just for the radio. Most of them also make special mixes geared toward TV. They may even tweak their mixes to make MP3 samples on their web sites sound their best.

The bottom line is what the rest of the world is trying to do is get one all-purpose super-hot mix and use it for all these applications (and more). Then everyone wonders why their stuff just doesn’t sound as good in one realm or another.
Leaving the studio with a nice hot (loud), crisp CD is certainly desirable for listening purposes and even for manufacturing purposes, but not for taking to a radio or TV station. On the TV front, I can think of one excellent example – have you ever tuned into a rap video and not been able to hear the vocals over the bass? Well, there you go.

The basic recommendation seems to be to take the radio stations a mix that has not been hard limited or clipped (the harsher forms of compression). Let the broadcast processors at the stations do their work. The result will be just as loud on-air as hypercompressed material, but will have far more punch, clarity, and life.

Compression can be abused, just like most things in audio. The best advice I can offer is the same as the oath doctors take – to first do no harm. Hypercompression can actually squeeze the life out of a performance by removing the dynamics altogether. Not only does that NOT sound very natural, it sounds pretty uninteresting. Everything at full volume all the time is pretty boring.

    Next time, barring any flooding of my mailbox with questions on another topic, we’ll be discussing more effects. As usual, you may contact me with topic suggestions or questions by e-mail at jennifer@doghouse1.com.