Speaker Positioning Science for Huge Arenas

Imagine being at a rock concert. The rock star lead singer is standing there at the center of a sports arena, shouting and singing as loud as they can. And while the fans in the front row hear you perfectly (all crystal clear for them), the fans in the very top set – all they hear is mumbled, distorted chaos.

You’d think they’d hear you the same way as someone closer, only perhaps a bit quieter, but that isn’t the case.

They hear a delayed flutter echo of it that bounces off the walls, then you’ve got reflected, refracted, and diffracted soundwaves arriving at slightly different times/phases, modal resonances, the jumbotron, the ceiling, variations of sound pressure level (SPL), and only then does it reach them. 

And by that time, it’s messy and off – a highly irregular sound field.

So how do you solve it? 

The Physics of Sound in Big Venues

The challenge of an arena really comes down to three things sound waves do. And all these things are a huge headache for engineers. 

First is the fact that sound naturally loses its energy as it travels. This means that, by the time it gets to the people in the back rows, it’s weaker and less clear. Second, all those hard surfaces like floors and the glass facades bounce the sound right back; they don’t absorb it. 

And what happens when sound bounces around? 

You get a chaotic tail of echoes and reverberation that makes the music messy and hard to understand. But this isn’t the end.

These direct and reflected sound waves then crash into each other, and when they meet, they either cancel each other out (these are ‘dead zones’, where you can barely hear) or they mix together and become incredibly loud, booming zones. That’s the reason for those tall, curved columns of speakers that hang from the ceiling, called line arrays. 

Engineers stack them vertically so they can laser-focus the sound and send it in a controlled vertical spread to cover the balconies. 

These suspended line arrays rely on precise stage rigging so they stay stable and properly aligned.

What Influences the Placement of Speakers in Arenas

The perfect speaker placement will depend on a few factors. So you can’t just look at where the audience is positioned and go with that. 

You’ll have to think about the event type, the audience size and positioning layout, what type of venue it is (hall, open, does it have walls/roof, and from which material are they made of, etc.), plus you’ll have to think about safety – no one wants a potentially falling speaker array as part of their event.

Let’s go over each in a bit more detail:

Layout and Size of the Audience

A packed crowd is great for revenue, but in terms of sound, it’s one giant acoustic dampener. On the other hand, if the arena is half-empty, it’s a reflective nightmare because those empty seats create too much echo. 

The system has to be adaptable and, more often than not, it needs to be adjusted in real time, as the venue fills up. 

Venue Architecture

Every building has a unique acoustic personality. Its shape (rectangle, dome, etc.) changes how the sound bounces, so that’s one more thing you need to factor in. Then there are materials, like concrete and glass, that create ringing echoes. 

This forces engineers to place speakers in a way that directly counteracts these reflections that could cause major issues. 

Event Type

The event itself is an important factor in sound design. Are we talking a rock concert? Is it a politician’s speech?

Depending on the type of event it is, the sound needs a powerful, full-body impact, or clear and directed (depending on where the audience is sitting/positioned). If the speech event has a concert as part of the show, then the sound system must be hybrid and easily adjusted. Booming music and clear announcements have different requirements in order to be done perfectly.

Safety and Load Management

This is a priority and it’s non-negotiable. 

The speaker arrays are extremely heavy, and they absolutely must be suspended over the crowd in a safe way. This is always the top concern for engineers; everything else is less important. 

The suspension system is so meticulously engineered that it’s incredible, but along with that, it’s also constantly monitored. This is how every single component stays secure and stable during the event. 

Touring Constraints

A touring production has a new acoustic environment to handle every night. For the crew, this means that they need to tweak their system to work with each new arena quickly. 

Luckily, there’s flexible hardware and sophisticated software that can make this happen, but it’s not easy to do. 

Conclusion

The next time you’re at a concert and you hear the performer clearly, hopefully you’ll appreciate that sound more because a lot of work went into it. 

Sound is tricky; you can’t see it, you can’t catch it, yet it jumps around all over the place like a crazy person. But with the expertise of many engineers and a lot of heavy (and expensive!) equipment, you get to have the perfect sonic experience