“I think people who work on architectural typology tend to divorce the buildings from the people who use them. It was especially a trend in studying church architecture for much of the 20th century to not discuss religion [that was practiced] in the buildings because discussing religion was not considered scholarly,” Gerstel said. “But these are churches, so to take out the ritual from the architecture means you’re not understanding the architecture correctly.”

To test Gerstel’s theory, the team spent hours every day measuring acoustical characteristics and recording performances of period liturgical music in nine churches in Thessaloniki, Greece, which was the second capital of the Byzantine Empire and where Gerstel studied at Aristotle University years ago. These churches have remained architecturally unchanged for hundreds of years and still have original paintings and mosaics on the walls.

In the church of St. Nicholas Orphanos, for example, the words of a hymn and chanters are depicted on the wall above a portal outside the central nave of the church. Gerstel said that she thought the placement of the painting was to signify where chanters were meant to stand when they performed.

To test her intuition, the team had a single chanter stand at the threshold of the opening to the sanctuary facing east, while Gerstel stood below the image of the chanters.

“The sound rolled out through the portal as if through a microphone,” Gerstel said, “as if the monks [in the painting] were singing.”

Every time the chanters performed, Gerstel said, the results were startling. The reverberating harmonies of liturgical chanting washed over them. Even when watching videos of the performances, each singer’s individual vocal part still cuts through clearly enough to be heard, almost as if a listener were to simultaneously look at a tapestry and its individual fibers.