The Technology Behind A Rock Concert Part 2: Sound

This is part two of our coverage of the technologies we got to see backstage at the Sweden Rock Festival. You can find Part 1: Overview here.

There were some truly amazing audio technologies in use at that festival. And guess what, I’m not even going to write about mixer tables and giant speakers. Intrigued yet?

The first thing I was shown made perfect sense at first, until it didn’t.

This here is a setup that monitors how many decibels are output from the concert. Since there are regulations regarding how loud a concert can be to be considered safe that makes perfect sense. But here’s the twist

The problem isn’t actually how loud the concert is at any given moment, but rather how many decibels are accumulated during the duration of the concert. Why? Beats me.

But this information gave a pretty interesting insight. At the end of the concert there’s usually a ‘buffer’ of decibels, so to take advantage of all their allowed decibels they often turn up the sound just a bit extra for the last song.

You might have noticed that but dismissed it, well now you know that it’s probably not just your imagination.

The next thing I was shown was in my opinion the very coolest sound tech I was shown that day.

Ajje Vikström from APM Pro Audio showed me a software called ArrayCalc. Using this software they can control with insane accuracy how far, and also where, the sound from the concert travels. This is referred to as array processing.

This can be achieved to some degree by optimizing the placement of the speakers in the array. But with the software you can go even further. You can see in the below picture how the sound was optimized to travel for this specific concert.

This to me explained how they can have multiple large stages so nearby each other, without the sound from one concert disrupting the other.

While I had heard of technology like this before, even used similar tech at home in the form of Audyssey. I had never thought about it being used on such a large scale, and with such accuracy.

Although this is a pretty simplified explanation of the technology. This video that Urban Näsvall, production manager at Sweden rock referred me to explains it in much more detail if you’re interested in the technical details.

However, the guy working at this station has more duties than building a good acoustic image. He can also digitally equalize the sound in real-time. After all, some songs require different speaker settings than others.

Of course they also had a guy with a huge mixer table standing there. But I imagine his work is more along the lines of fine tuning the sound, and changing levels of individual channels, fading in and out, etc. He also had a close watch on the decibel counter, so I suppose he also works to stay within the legal noise limits.

These were the technologies that stood out from what we already expected to see, giant speakers and giant mixer tables. But even though there’s not that much to say about them, we admit they’re pretty cool to look at, so here’s a peek at some of them. Pretty impressive setups for sure.