In Istanbul, Turkey, stands one of the architectural wonders of the world, glorious but silent. 

It is the Hagia Sophia. This cathedral built in 537 boasts an enormous dome, representing the vault of heaven. Within, beams of light pour through many windows into a vast space. A beautiful sight—but this grand structure is not just for looks. The space was designed to reverberate with sound. For nearly a thousand years, Christians worshipped in the Hagia Sophia, like in other churches. But when they sang, the sound was truly unique.

Sadly, true Christian worship in the Hagia Sophia was silenced long ago. In 1453, the Ottoman Empire conquered the city of Constantinople. The Ottomans were Muslims. They changed the city name to Istanbul and converted the Orthodox Christian cathedral into a mosque. Now it is a museum, and music is banned.

So what did music in the Hagia Sophia actually sound like? With the help of a choir, advanced recording technology, and a balloon, we can hear for ourselves. 

Two Stanford University researchers from seemingly unrelated fields came together to produce the forgotten sounds. Art historian Bissera Pentcheva met Jonathan Abel from the computer music department. In discussing the missing music, Abel realized he could recreate the acoustics of the Hagia Sophia digitally.

First, the pair made a digital impression of the cathedral’s acoustics . . . by popping a balloon. The POP! from a balloon varies depending on the room as sound waves hit and bounce off surfaces. Abel says in an NPR interview, “The space interacts with the sound, bringing back . . . information” about the room. Pentcheva went to the Hagia Sophia with a balloon and a few microphones. After museum hours, she popped the balloon. The explosion of sound echoed nearly 10 seconds in the cavernous cathedral.

Using the balloon recording, Abel constructed a digital filter that can make any recording sound like it is inside the Hagia Sophia. The Portland, Oregon, choir Capella Romana recorded an album with this filter, using music once sung in the cathedral. For the first time in hundreds of years, we can hear the glorious music meant to fill the Hagia Sophia.

“It’s actually something that is beyond humanity that the sound is trying to communicate,” says Pentcheva. She is right. Hagia Sophia means “holy wisdom.” The cathedral, with its great dimensions and rich acoustics, points to the wisdom of God. As awe-inspiring as it is, though, the sights and sounds of this man-made stone cathedral are only a pale representation of what is to come. Imagine the sounds of worship in the presence of the infinite living God!