Over Compression and The Loudness War

While mastering the tracks on my latest CD release (shameless plug: It’s All Timing), I was doing some research on average loudness, in order to determine what I should be shooting for with the final tracks. I stumbled upon something called “the loudness war.” Basically the battle between audio aesthetics, and the benefits of compression and limiting.

Just because we have the technology to master music louder doesn’t mean we need to blow the windows out of the house. A lot of commercially available music has been ruined, in my opinion, by the ability of mastering engineers to push the audio signal level as high as possible. Balls to the wall is an understatement.

I love loud music as much as the next metal head, but when it’s so over-compressed that the dynamics are completely lost we’re missing something. The subtle nuances of an acoustic guitar part do not need to be the same amplitude as a drum solo, but that’s exactly what we get when these mastering tools are overused.

Why are things over-compressed? It’s mostly a result of having the technology to do it. Today’s digital audio technology allows us to push the signal level higher and higher. Basically, we can make quiet parts really loud while holding the louder parts where they are. That’s compression. To prevent clipping of the signal we can apply a limiter, which keeps signal peaks below a specified threshold.

It’s good to have this kind of control over the sound, it allows music to be appreciated at lower volumes, on various systems. A tool called an adaptive limiter can squeeze even more out of the song, and it’s used a lot in modern mastering to get the apparent loudness of the music even louder.

I remember the special note on the self-titled debut CD by Rush back in 1974. It said “For best results play at maximum volume.” The limitations of the medium (vinyl record albums), and the technology at that time preserved much of the dynamics of the original recording. Listen loud and it sounded fuller because you could hear all of those nuances and dynamics that you might miss at lower levels.

Compression and limiting became popular for radio stations because they could ensure a louder, more even signal output, regardless of the varying levels of records that they played. These technologies increase the average loudness of the signal, and allow radio broadcasts to be heard better on smaller radio sets and car speakers. The compression technology essentially sacrifices dynamics for loudness, but to what extent is entirely up to the mastering engineer, the band, and radio stations.

The advent of audio tape allowed for greater maximization of the signal. You remember Max Headroom? What the term headroom originally referred to is the saturation limit of the audio tape medium. Compact disc and digital technology provided greater headroom to expand into. Saturation distortion isn’t a problem on CDs, but over-compression can still lead to clipped signals, and clips create distortion.

Unfortunately radio stations of today completely over compress the sound and all dynamics are pretty well scrapped. The music can even seem unnatural, with pulsing effects, depending on the levels of compression and limiting used. That’s why mastering engineers tend to master the music with high compression and push it with limiting. The louder they make it, the less likely it is to be altered with when played over the radio.

But how loud is loud enough? Why push so far? I’ve looked at pro recordings in my audio editor and have seen incredible amounts of signal clipping. Clipping is distortion. Why would a commercially available recording be distorted? That seems to go against the “pro” in professional audio production.

So, on goes the loudness war. Some bands are choosing dynamics over loudness, and having their music mastered at a lower average volume. Still, others just like it loud for loudness’ sake. The problem is that the consumers end up having to turn their volume up and down depending on what CD they’re playing. But I guess even that won’t be a problem for much longer, since apps like iTunes can automatically adjust track volumes for a more consistent listening experience. Leave it to technology to smooth out the wrinkles created by technology. If that makes any sense.

I guess the purist in me argues to make it louder but keep the dynamics as much as possible. Push it a little, but don’t push it too far. But hey, what do I know? I’m no pro.