99% Invisible - 236- Reverb

Episode Date: November 16, 2016

Through a combination of passive and active acoustics, architects and acousticians can control the sounds of spaces to fit any kind of need. With sound-proofing and selective-amplification, we can add reverb or take it away. We can make churches sound … Continue reading →

This is 99% invisible. I'm Roman Mars. And I'm sitting in a tiny little room with this microphone right up to my mouth so that the sound of my voice is transmitted directly from me to you. There's no sense of the room that I'm in. When I stop speaking, the sound stops. There's no reverberation, no reverb. Roman and I are both talking in rooms outfitted specially for recording. verb. Roman and I are both talking in rooms outfitted, especially for recording. Rooms, that sound good. That's producer Avery Truffleman. Because if I step outside this tiny, completely padded studio, okay, it's still quiet because I'm inside, but I'm gonna walk around a little bit so you can hear the architecture around me. You can tell now that I'm in a bathroom, or you can tell if I enter the stairwell outside our office.

And if you're not listening in headphones, my voice is bouncing around your car or whatever room you're in. Whatever you're hearing, sound is affected by the architecture. There are two main ways to control the sound in a building. Active acoustics and passive acoustics. Passive acoustics are the materials in a space, like the padding in the studio room. Carpeting and drapes are also

absorptive materials that soak up sound. Glass and porcelain, on the other hand, create more reverb. Essentially, if it's shiny, it's going to be reflective. It is an easy way to interpret that. This is Ashley Hansen. My name is Ashley Hansen. I'm the Design Services Manager at Myersound. Myersound is a company that mostly makes active acoustics,

which is to say speakers, amplifiers, and other electric sound equipment. People probably have run into our products. They just don't know that it's mire sound. Mire sound makes a lot of the big speakers hanging off of the ceilings at concerts and Broadway shows. But their products are also in a lot of unexpected places. Crew ships, restaurants, we are in some corporate headquarters, educational facilities, airports. Over 600 Myr sound speakers were used

when the Pope spoke in Mexico. One of the things I tell people in general is, if we're doing a job right, you might never notice that we're even there. And that's part of Ashley's job at Myr Sound. To make sure the sound equipment is effortlessly integrated into a building using both passive and active acoustics, materials and electronics. But often in architecture,

what looks the best is at odds with what sounds the best. Of course you don't necessarily want to always see the big black speakers somewhere, and so we have to get creative. We like our speakers out of sight. And we also like high ceilings and long glass windows, which make spaces sound really reverberant. So architecture is a puzzle for Ashley and her team to solve. Whenever we see rooms that have curved walls, we kind of cringe, especially if they're out of glass. Oh, that's pretty. When we approach spaces, there are things that, we kind of cringe, especially if they're out of glass. Oh, that's pretty.

When we approach spaces, there are things that, although they're beautiful, we know are going to definitely put pressure on us to come up with creative and unique ways to appease the visual and sonic needs of the room. So it depends on what you're trying to do in that space. If it's a venue for the symphony or the opera, you want the sound to be big and resonant and echoing. For a cafe or a place with acoustic performances, a little reverb is nice. But if you're trying to hear a lecture or a reading or say, have a meeting, you probably don't want much reverb at all. But we haven't always been able to precisely control the acoustics of a building. Sound,

until fairly recently, was a somewhat mysterious element in architecture. In the late 18th century, there are all sorts of different theories about how to get good sound, but half of them contradict the other half, and no one really knew what to do. This is Emily Thompson. She's a history professor at half, and no one really knew what to do. This is Emily Thompson. She's a history professor at Princeton, and a scholar of sound technology. And she says, at the turn of the 20th century,

architectural acoustics are pretty much a role of the dice. Architects begin to fret that they don't really know what they're doing with this aspect of their designs, and it was all kind of left to chance. And if you were lucky, your theater would sound good. And it was all kind of left to chance. And if you were lucky, your theater would sound good. And if you were unlucky, it wouldn't.

And in 1895, Harvard University was very unlucky. The university had just completed building the Fogg Art Museum. And it had a lecture hall where there was so much reverberation that they simply could not hold classes in that room. You couldn't understand this feature because there was so much reverberation that they simply could not hold classes in that room. You couldn't understand this feature because there was so much. The room was very confusion.

Harvard had just wasted a lot of money on a completely useless room. Sound had ruined it. And in an attempt to save the space, they listed the help of a rookie physics professor who had some time on his hands. So the president of Harvard asked this young physics professor to figure out how to fix that auditorium and make it usable teaching space. This professor's name was Wallace Sabine. And through this task, Sabine would eventually become the father of architectural acoustics.

This sent Wallace Sabine onto an investigative path that actually took several years collecting data. Basically making sounds in rooms and timing the reverb. He would take measurements of the different reverberation times in different rooms all over campus, and in order to do this under the quietest possible circumstances, he tended to run his experiments in the middle of the night. And he would change the reverberation time within a given room by bringing into it various sound absorbing materials. Sabine was a perfectionist. He threw out over 3,000 measurements after determining that his own clothes had a small effect upon the sound of the room. He started all over again, taking measurements in the dead of night, but now wearing the

exact same outfit every time. Meanwhile the President of Harvard is waiting and waiting for this lecture hall to be made useful again. At one point, he finally says to the young professor, it's time for you to tell us what to do here. Enough is enough. And that night, feeling nervous under pressure, Sabine pours over his notebooks and has a breakthrough.

Looking at all his measurements, he starts to notice a trend, a mathematical relationship between the size and materials of a room in its reverberation time. A relationship so steady that you can make a formula out of it. He discovers a mathematical formula that connects the architectural materials of the room and the behavior of sound within it. And this is a formula known as Sabine's formula now that really enables people to be able to predict the reverberation time of a room based on its design. Sabine's equation allowed for planning. Suddenly you could manipulate the reverb of a space by changing the materials the room was made of.

So that then you can take any sort of architectural plan, you know, the dimensions, you know, how many square feet of plaster or wood or glass or upholstered seats, fill this room, and you can just kind of plug and chug, and the formula will turn out a predicted number for the reverberation time of the room. Sabine's formula helped architects design for as little or as much reverb as they wanted. Architects could now control the sound of a space. They could make big rooms with very little reverb. And so they begin to do just that. And the most remarkable early example of this was St. Thomas Church. St. Thomas Church, which is in New York City,

not far from the Museum of Modern Art. The architects of this church wanted to build it in a neo-gothic style, basically to make it look like a European cathedral, made of stone with high sea leans and stained glass windows. But while they wanted this building to look Gothic, they realized that a Gothic sound would not work for a modern Protestant service.

They wanted to hold a much more sermon-focused service, not just a medieval mass. It needed less reverb so parishioners could understand the words. So the architects turned to Wallace Sabine to make a sacred space that would be clear, calming, and reverb free. Sure, Wallace Sabine could add felts

and padding to the building, but he thought that didn't fit the feeling of a church. He worked with a tile maker to come up with special sound-absorbed of ceramic tiles with porous surfaces. He called them Rumpford Tiles. Rumpford Tile, they named it after a physicist who had kind of been interested in solving practical problems, and it's a substantial architectural material. It's not a matter of

just hanging drapes or tacking felt onto a surface. It's much more integral. So with St. Thomas Church, by using these sound absorbing tiles way up in all the ceiling vaults, they had the Gothic look without the Gothic sound. St. Thomas Church was completed in 1913. It's definitely not modern looking, but it was a landmark modern sounding building, completely engineered and formulated for environmental control. Thanks to the Rumford tile.

Sabine worked in public and private spaces all along the East Coast and came out with more products to accompany the Rumford tile. And he passed away in 1919, right really at a moment when a much more pervasive interest in controlling environmental sound would come to the fore. The roaring 20s. It got that name for a reason. It may very well be the case that it was louder in the 20s than now.

This was in era when cars and trucks did not uniformly come with mufflers. There were these new unfamiliar, unprecedentedly loud sounds of cars, of trains, of industrial machinery, of construction, of skyscrapers rising everywhere, and in the crowded city an escape was hard to find. An escape was hard to find. Sound crispness and clarity could provide calm and control. It meant a complete mastery of the environment. And so the desire to control sound within interior spaces is in part a kind of a drive to create refuge from the noisy tumult of the world outside.

Rumford tile launched an industry. By the 1930s, dozens of different corporations were manufacturing and selling vast quantities of acoustic building materials, with names like Acoustolith, Acousticello-Tex, and Sabonite. For those who could afford it, you know, whether you could buy a soundproofed apartment or just enjoy quiet offices or theaters. Quiet became a luxury commodity. Acoustic materials were so advanced that Sabon's formula couldn't apply anymore.

By 1930, you're really able to create spaces that simply didn't exist in the 19th century. Sabine's equation doesn't work particularly well. It was a product of the world in which he did his investigation, which was still that 19th century world filled with glass and wood and plaster. All this new acoustic technology was able to create a level of silence unprecedented in Sabine's time. Finally, it was quiet. Too quiet. But as the 20th century went on, people became disenchanted with the idea of completely

closed off spaces with dampened acoustics. They wanted to let in air, light, and sound. Interestingly, by the 1970s, some of the cultural factors and the aesthetic preferences of people with respect to sound design had changed since the early 20th century. And in some of these spaces, including St. Thomas Church, they actually decided they wanted more reverberation than this material engendered.

So in some cases, the porous surface of the rumford tile has been painted over to kind of seal off those pores and to make it more reflective of sound. And these days we want our architecture to have a range of reverb. Now one single room or venue can accommodate a lot of different kinds of sounds. And that's possible using not just passive acoustic materials like the one Sabine pioneered, but also active acoustics. one's Sabine pioneered, but also active acoustics. Using microphones and loudspeakers and digital signal processing.

That's Melody Parker, an acoustic engineer at Myersound. And they have this product called Constellation. And so what Constellation allows you to do is to create multiple environments in one space. It basically allows you to manipulate the sound of the room completely digitally, through a system of many tiny speakers and microphones. Where are the microphones?

Throughout the ceiling. They're really small. Melody showed Avery the test room for consolation inside Meyer Sound's headquarters in Berkeley. It looks like a very small theater. It's a room with a low reverb time, thanks to much acoustic padding. But it's outfitted with a variable active acoustic system, where tiny microphones capture the sound, and the speakers play back those sounds to mimic the reverberation in different sized rooms.

I should demonstrate. Yeah. Okay, so I'll grab. Melody took out an iPad and activated different settings, which completely changed the sonic shape of the room. I now do a dramatic demonstration. This is what it sounds like with a very long reverberation time. Melody played the clave to demonstrate the reverb time.

This setting was called Sacred Space, and it gave this tiny room the sound of a cathedral. And it's one thing to hear a reverb effect in a song or a podcast. It's another thing entirely, to experience a reverb effect in a room, in real life, in real time. The echo completely changed my perception of the space. Then melody took the reverb completely out of the room just entirely, and suddenly it felt stifling, like I'd been muzzled or something. It was hard to breathe. And those are some of the most dramatic settings on constellation.

There are lots of subtle changes that a client could make to a room. They have the ability to change the length of the reverberation, change the strength or the loudness of the reverberation, change the strength or the loudness of the reverberation, and to even change the perceived height of the room and the perceived width of the room. Constellation in its competitor sound systems are expensive, so they're not common exactly, but they're in a lot more places than you'd think, like a number of big venues all over the world, and classrooms, and offices. Restaurants use so-called variable active acoustics, so they can adjust the noise level to keep it in a pleasant hum, regardless of how many people are in the space. And the architectural implications of this are fascinating. Of course, architects and acousticians

still have to pay attention to the passive acoustics and the building materials, but there's a lot more design flexibility now. Yeah, we actually have an interesting one that we're working on for a tech business where they took over an old factory. That's Ashley Hansen at Myr Sound again. And so the challenges in that space,

it's the factories all brick and exposed and beautiful and have these high ceilings. And she says a combination of active and passive acoustic systems help architects repurpose old buildings. We're able to take spaces that would never be used for certain applications and make them great for all sorts of different events. And that wouldn't happen before. This office space in this old factory would just be a reverberant nightmare.

No one could focus. And they probably wouldn't have purchased it for that. Buildings like St. Thomas Church marked the beginning of our quest to control sound in the built environment through passive acoustics. Now, a hundred years later, with advanced active acoustics, we can separate sound from space. Warehouses can be made to sound like opera houses, and opera houses can sound like small clubs. It's just a matter of how much reverb we want.

In this episode we featured some actual sounds from New York City from the 1920s and 1930s. You can find them on this incredible interactive website that Professor Thompson made in collaboration with the University of Southern California. It's got a map of New York and you can click around it to see what it looked like and what it sounded like in the 20s. And the easiest way to find it is to go to shutoutthenoise.com. Seriously, check it out, super cool. Shutoutthenoise.com.

Special thanks to Ben Strange, Alex Stoll, and everyone at Myersound. 99% Invisible was produced this week by Avery Truffleman, which refused Seth Katie Mingle, Kurt Colestet, Sam Greenspan, Emmett Fitzgerald, Terran Mazza, Delaney Hall, and me, Roman Mars. We are a project of 91.7 K-A-L-W in San Francisco and produced on Radio Row, in beautiful, downtown, Oakland, California. You can find the show and join discussions about the show on Facebook. You can tweet at me at Roman Mars and the show at 99PI org. We're on Instagram and Tumblr too. But the Nexus of all things 99PI is at Radio Tapio.

From PRX.