How ancient churches sounded

Church buildings are acoustic spaces, in which music is performed.  Researchers are studying the acoustics of ancient and medieval churches.  They are finding that certain design elements were intended to adjust sounds, “trying to tune the space.”

Moreover, the acoustic data they are uncovering enables the researchers to reproduce the effects electronically.  Once a digital signature is discovered, it is possible to play recorded music–say, Gregorian chants–and filter it so that we can hear what it sounded like in that particular building.  “It’s like time travel,” says a musicologist.  We can make “a museum of lost sound.”

 From Adrienne LaFrance, Mapping the Acoustics of Ancient Spaces – The Atlantic:

Even before their technical analysis began, it was clear that these ancient spaces were designed to shift a person’s sensory experience.

“You cross the threshold and your eyes immediately have to adjust,” Gerstel said. “It seems pitch black inside. The first thing you notice is images of saints, who are your size, staring at you. Gold halos against dark background, and they seem to loom. It smells of incense. You’re in this world of myrrh. The temperature is different as well. Inside, you’re in a much cooler space. Your entire body adjusts … and then to have music at the same time? That hits every sense.” . . .

To map the acoustics of ancient spaces, to understand how a church was designed to reverberate at certain frequencies, Kyriakakis and Donahue gathered what’s called an impulse response. To do that, they placed loudspeakers omni-directionally throughout a church. Then, over the loudspeakers, they broadcast a test signal, like the one Donahue described in Hagia Sophia. “It’s a very long chirp that starts at low frequencies and goes up to high frequencies and it just sweeps through, like a whooooop,” Kyriakakis said. “And you record from various locations with microphones to see what happens to that chirp as it bounces around the church.”

The data showing what happened to the chirp in each part of the church is fed to a computer, which then registers the impulse response for the unique space. And here’s where it gets really interesting: Once you have a building’s impulse response, you can apply it to a recording captured in another space and make it sound as though that recording had taken place in the original building.

“So you can take chanters with the original [Byzantine era] music and put them in a studio that has no acoustics,” Kyriakakis said. “They can sing a chant, and then we can process it … and all of the sudden we have performances happening in medieval structures. It’s like time travel to me.”

The implications go far beyond the ancient world. Kyriakakis, Donahue, and Gerstel imagine creating a catalog of impulse responses for historic buildings, then recreating the sounds of those structures in what would be, essentially, a museum of lost sound.

[Keep reading. . .]