Acoustics in Architecture: How Spaces Shape the Sounds We Hear

Before Notre Dame Cathedral’s fire in 2019, sound traveled throughout the sanctuary so efficiently that a cough or heel tap could be heard for eight seconds. Visitors lower their voices and measure the force of their footsteps.

Whether on purpose or not, the cathedral’s design uses sound to influence behavior. In a cathedral, the mindfulness one has to take with motion, speech, and breath becomes a compass for how visitors feel. It’s unlikely that the original builders of Notre Dame had an acoustician on staff, but architecture has been used to manipulate sound for centuries.

In this article, I’ll show you some examples of how acoustics and architecture work together and then show you how to take these concepts and put them to work to improve your podcast. 

How Does Sound Travel? 

Before we get into architecture, let’s think about how sound works. If you’ve read our article about what is reverb and how to tame it, you know how sound works already. To [over]simplify:

• Sound travels spherically from a source until something (like a surface) reflects or absorbs it. 
• Different surfaces make sound react in different ways. The harder a surface is, the more it reflects sound waves. The softer it is, the more it absorbs. 
• Smooth surfaces reflect sound in a direction. Irregular surfaces break up sound waves and reflect sound in many directions.

If you’ve ever screamed into a pillow or shouted while walking through a tunnel, you can imagine how this works.

How Can Architecture Change Sound?

Now that you know how sound travels, it shouldn’t be hard to visualize how cathedrals like Notre Dame use the relationship between acoustics and architecture to influence behavior. High ceilings and hard surfaces can amplify and sustain a note in a hymn, or words in a homily.

But, how has architecture been used to influence clarity or tone? Here are some examples.

The Theatre at Epidarus: Amplify and Filter

Photo by Carole Raddato from FRANKFURT, Germany

Over 2,400 years ago, Polykleitos the Younger designed The Theatre at Epidarus, with acoustic marvels that are still studied today. 

Location affects some of Epidarus’ acoustics. The shape and slope of the west side of Cynortion Mountain, next to the amphitheater, and the wind from the Saronic Gulf, may influence how the performers’ sound travels. But terrain and weather aren’t responsible for everything. The amphitheater’s bowl shape reflects sound up and out, so the audience in the fifty-fifth row can hear the performers as clearly as the audience in the first. 

One standout detail, however, is the seating. In 2007, researchers from the Georgia Institute of Technology determined that “the rows of limestone seats at Epidaurus form an efficient acoustics filter.” Higher-frequency sounds (from the performers) bounce off the limestone benches, and the sound waves move upwards and toward the back row. Lower-frequency sounds (such as audience murmur or the occasional cough) don’t reverberate as effectively with the corrugated surface of the limestone benches. 

The Ancient Greeks built acres of amphitheaters, but later benches used different materials, such as wood. While this is undoubtedly more comfortable, none of these amphitheaters have the acoustic clarity of the Theatre at Epidarus. 

The Temple of Kukulcán: The Earliest Tweet

So, you can imagine how sound reverberates off flat, hard surfaces. We also discussed how limestone steps elevate high-frequency sounds while dampening low-frequency sounds. What if architecture could harness acoustics to make a particular sound?

The Temple of Kukulcán at the Mayan site of Chichén Itzá in Mexico is a step pyramid, built out of limestone, topped with a flat-roofed temple. This pyramid honors the feathered serpent deity Kulkulcán, related to Quetzalcoatl, an Aztec deity who also can take the form of a feathered serpent. Why am I telling you about Mesoamerican myths and legends? Hang in there; I promise, this is worthwhile. 

The Quetzal is a sacred bird in Mesoamerican culture, known for its brilliant tail feathers and unique call; a high-pitched zippy sound. You can hear this birdcall by finding a Quetzal in the wild. Or, stand at the foot of The Temple of Kukulcán. If you clap your hands while standing near the temple (as many people do), the resounding echo sounds like the call of a Queztal. 

Don’t believe me? Sound up, please:

You’re welcome. 

Did the Maya purposefully build the Temple of Kulkulcán with limestone steps that could filter sound into a bird’s call to honor a feathered serpent deity? Do the windows and doors of the temple affect the function? Again, we don’t know for sure. But the Mayans did use calendars, mathematics, and written language by 250 BC, much of which was destroyed. They may have known a lot about acoustics and architecture that we don’t. 

Heatherwick Studios: [How] Can You Hear Me Now?

Today, we can control traveling sound waves with acoustic treatment, such as desktop workstations or curtains. We can also capture, amplify and direct it electronically. But, subtle details in building materials still make a big difference in sound today. Take, for example, Heatherwick Studios in London. 

When architect Thomas Heatherwick designed his studio, “shared spaces were carefully considered and arranged to achieve the right levels of sound wrapping and containment, and evoke a sense of connectivity.” The builders sand-blasted the concrete beams in the foundation, revealing an irregular surface pockmarked with shingle from the River Thames.

“Immediately, the sound waves that hit that are broken and fragmented because you don’t get a singular reflection coming back at you,” Heatherwick said. The diffusion of sound waves results in a more harmonious workspace. Acoustics and architecture aren’t the only aspects of Heatherwick’s designs that work together to inspire people, but they make a big difference. 

What Does The Relationship Between Acoustics and Architecture Mean for Podcasters? 

You may be looking around your podcast recording space now and thinking, “Oh, dear.” I know I am: my studio has nine-foot ceilings. But, there are many ways that humans can take advantage of architecture to improve their podcast sound. 

Here are some things to consider:

Where Do You Record Your Podcast?

Ever notice how many ads for podcasting equipment show stock photos with people recording in their living rooms? Open-plan layouts with high ceilings and hard floors are popular among real estate developers, but these are less than ideal for podcast recording. 

Think about the smaller spaces in your home. Closets toward the center of your dwelling are less likely to share a wall with the outside world. Does your home have a closet that you can re-purpose into a cloffice? If you’re stuck with a large room, build a blanket fort. There are loads of ways to build a silent home studio that sounds great. 

What Are Your Surroundings Like? 

I live on a downhill slope, and the house just downhill from us has a wide, flat yard. The gentleman who lives there absolutely loves his gas-powered leaf blower. Nothing brings him more joy than to blast that flat lawn with air until he exsufflates each and every speck of debris from his domain. A low wall divides his flat lawn from my slope.

Now that I’ve learned about the stone steps of The Theatre of Epiudarus and the Temple of Kukulcán, I wonder if that stone surface drives the higher sound frequencies from his yard equipment toward my windows.  In any case, this man’s lawn-care habits have taught me not to record on the northeast side of my home. 

What surrounds the building where you record? Which parts of the building are far from noise? Typically, bedrooms (or bedroom closets) may be further from the street, and make quiet recording studios. Basements, too, can be good since they’re underground. But if your basement has noisy HVAC machines, maybe not. Only you can decide how to make acoustics and architecture work together for your specific situation. 

The Heck With Architecture, Record Outside

If you feel as though this fits your podcast, record outdoors. The lack of walls and ceiling means nothing for your voice to bounce off of. You can also capture natural sound elements that enhance your podcast. Grab your phone and a tiny kit like the BOYA Mini or Rode Wireless Micro, and you’re all set.

Why Do Acoustics in Architecture Matter?

Ancient and modern structures can teach us so much about how sound works. Granted, none of us are recording regular episodes in the Theatre at Epidarus, but we can always stay on the lookout to use our environments to our advantage. Understanding audio is a major part of this.

Acoustics in architecture is just one element in the fascinating world of audio. In 26 Fascinating Facts About Sound, you’ll learn about how sound can break glass, levitate objects, and even put out fires. What a podcast episode that would be, eh?