Monks in Byzantium said it was the gently pulsing rhythms, uplifting melodies and resonating harmonies of liturgical chants floating through the corridors, sanctuaries and domes of their brick and stone churches.

But in 2015, with advanced recording and acoustic measuring technology now available, what do we really mean by angelic sounds? UCLA Byzantine art history and archaeology professor Sharon Gerstel and a multidisciplinary, international team of scholars have devoted much of the last year trying to find that out.

“We wanted the best scientific testing possible to understand what it meant when the Byzantines said, ‘It sounds like there are angels in the buildings,’” Gerstel said.

So Gerstel and a team that included an audio and acoustics professor from USC, a recording engineer, an archaeologist, an architectural historian and a musicologist who specializes in transcriptions of 14th-century Byzantine music spent two weeks in northern Greece last summer trying to capture the ethereal.

The 14th century was significant to the team’s work for several reasons: It marked the end of a five-centuries-long period when Byzantine churches were shrinking in size. In that time period, the paintings and mosaics in these churches depicted the singers as well as the lyrics of the chants. And the music in Byzantium changed into a form called kalophonic (beautiful voice), putting the emphasis on soloists who would riff on the music and create beautiful melodies.

Previously, scholars had said the move to build smaller churches was the result of congregations or monastic communities getting smaller, Gerstel said. But with artwork incorporating inscriptions from hymns and depicting figures gesturing to one another from opposite walls in churches as if they were conversing, Gerstel posited another theory: These new churches were designed to be smaller — and even decorated differently — to enhance the performance of the chants.