There are few experiences as memorable as attending your first concert in an arena. You enter the doors of a cavernous dome and squint to find the section and row of your seat on your ticket. You take your seat, the lights dim, and the rumble of bass being pumped through a dozen loud speakers pounds in your chest.

Before this sound reaches your body, it must travel through a complex system of electrical equipment — the sound system — that allows engineers to manipulate how the sound emanating from stage is delivered to the audience. But before any sound equipment is brought into an arena, engineers must first determine the venue’s acoustics.

“In the arena, the main goal is to make everybody understand and hear everything perfectly,” says Herbie Woodruff, crew chief and sound engineer at Target Center. To accomplish this, there are a few obstacles that engineers must overcome first.

Arenas, by nature, are large spaces designed for seating thousands of people. As such, sound must be delivered at loud volumes so that it has enough energy to reach its destination. However, loud sounds and large spaces create the perfect mix for reverberation — a sound engineer’s nemesis.

When sound hits a hard surface like a concrete wall, it reflects rather than absorbs. As it bounces back into the arena it creates an echo, which makes the space louder and muddies the sound quality. The Xcel Energy Center combats sound reflection by utilizing an open design, explains Mark Anger, facilities development project manager for Minnesota Sports and Entertainment. The open suites let sound pass through unobstructed, and the open concourse (there are no walls separating the arena’s concourse from its bowl) drastically reduces the amount of reflective surfaces.

Further enhancing Xcel’s sound quality are the acoustic panels covering the walls. Each panel consists of a layer of insulation encased by perforated metal sheets, creating a porous surface that absorbs sound rather than reflects it. Acoustic banners called lapendary panels also help—they cover the entirety of the arena’s ceiling and “reduce the reverberation time and sound intensity levels in normally bad acoustical environments,” explains Anger.

Let’s get technical

A sound system starts with its sound sources — microphones, keyboards, guitars, etc. — which are sent as inputs to the mixing console. The sound engineer overseeing the console can manipulate the sound as needed before it’s converted into an output and sent to a power amplifier. The power amplifiers boost the volume of the outputs and send them to the final component of the sound system: the speakers.

There are two main types of speakers: house speakers, which carry sound out to the audience, and monitors, which deliver sound back onstage to the performers via onstage speakers at performers’ feet or in-ear monitors, which are worn like earbuds. Although the audience doesn’t hear the sound emitted from monitors, they are crucial in creating a seamless performance onstage. “When you have people spread over a 40- or 70-foot-wide space, it’s easy not to be able to hear the guy on the other side of the stage,” says sound engineer Jim Pfitzinger. “Trying to keep everybody in time across these large distances is sometimes a problem.”

House speakers vary widely in type and configuration, but today many venues are moving toward line array technology—a powerful configuration of speaker components that look like long, skinny lines of boxes strung together and usually hang on either side of the stage. All of the individual components are “specifically coupled together and become a really powerful and directional tool,” Pfitzinger explains. “All of those components are timed and aligned to act as one large component to give you a more consistent coverage from the front of the venue to the back of the venue.”

Engineering the show

While every arena has its own in-house sound system, which is used mainly for sporting events, when an artist comes to perform they usually bring their own equipment and sound engineers. Artists will trek across the country in semi-trucks with their entire setup — everything from microphones to speakers and amplifiers. When Lady Gaga came to the Xcel Energy Center she brought 27 semi-trucks with her; Justin Timberlake rolled up to Xcel with 32. An artist will also bring five to six engineers with them to run a concert, with the venue providing eight to 12 people to help set up.

Working as a touring sound engineer means running the same show every night. Although touring engineers work in a different arena on each stop of the tour, they are always working with the same equipment and the same artist.

Being a house engineer, however, means constantly switching gears. As a house engineer at Xcel, a normal work week for Pfitzinger entails running sound for the opening night of the Minnesota Wild one night and Sesame Street Live! the next. “You’re going to be doing a different gig every night; sometimes three different gigs during a day,” Pfitzinger says.

In addition to working a wide array of events, being a house engineer also means constantly working with new sound systems and touring engineers, Pfitzinger says. “As a house guy, you’re going to see maybe 300 different systems over a year and a half, and 300 different engineers. You see a lot of new technology.”

Engineering sound is a science, and requires a great deal of precision. However, everyone experiences sound differently — what sounds good to one person may be off-putting to the next. Working as a sound engineer often means deferring your own judgment and listening to the artist.

Herbie Woodruff learned first-hand how to design for a musician’s preferences by running sound for Prince. “I worked with him a lot before he became a big artist, and through his whole career,” says Woodruff. “He was responsible for how he sounded. If you were the sound engineer, you and him agreed on how it sounded. And really, that’s how he wanted it to sound and you couldn’t change it. If you did, he’d fire you.”

Being a sound engineer at an arena means always adapting. Monitor engineers must constantly check that performers can hear each other in time. The front of house engineer has to ensure that all the inputs are delivered to the correct speakers at the exact right moment. House engineers see hundreds of systems each year, and touring engineers work in a different venue every night. But if they do their jobs successfully, all of this will occur without the audience ever realizing it. The crowd will shuffle out of their seats at the end of the night, reveling in the sounds that they just heard, without ever knowing who delivered them to their ears.

Colleen Cowie runs the blog Pass the Mic. This article was produced as a part of a collaboration between The Current and The Growler, a monthly craft beer lifestyle magazine covering the best stories in beer, food, and culture. Find this article online and in print in the November edition of The Growler.