A donkey strolls past me nonchalantly. I laugh, watching the beast tackle the cobbled streets of Istanbul’s Old City with a curious grace. I can hear prayer songs emanate from some of the most ornate places of worship in the world.
Home to over 13 million people, Istanbul is an intriguing metropolis of extremes. It is sliced by the Bosphorus Strait – a 32 kilometer body of water that divides Europe and Asia. On one side of the water sits a cosmopolitan city, complete with bars, high fashion stores, coffee shops and art galleries. Across the river, however, lie the ancient remains of the Old City. It’s here that the stunning Hagia Sophia can be found.
Built in 537 AD as a church during the Byzantine Empire, Hagia Sophia was converted into a mosque almost a thousand years later by the Ottoman Empire. Finally, in 1935 it became a museum. The tiled mosaics and intricately carved archways are entrancing, but the site’s final transformation into a tourist attraction has removed some of Hagia Sophia’s charm.
Information signs and historical photographs dotted around the museum are distracting. I want to see the building during its religious hey-day, and hear the echoes of ancient songs bounce around these walls.
Claus Lynge Christensen, an acoustic engineer at the Technical University of Denmark, is also interested in resurrecting the sounds of Hagia Sophia. A decade ago, Christensen and colleagues began converting Turkey’s ancient buildings into computer models. The ultimate goal was to map the acoustic signature of the sites, says Christensen, “making it possible to hear how the buildings sounded in earlier ages”.
A key to this process was mapping a room’s reverberation time, which is a measure of how sounds fade away. A high reverberation time means sounds drift off slowly, making noise linger in a room — an effect you might want in a concert hall or prayer room, for example.
The reverberation time is affected by the textiles used to decorate the floor, walls and ceiling. Consequently, Christensen and his team painstakingly documented the materials that created the surfaces of Hagia Sophia over its lifetime. For example, when it was a church the floors were covered with hard marble, which was replaced with carpet once the building became a mosque. In total, almost six thousand surfaces were used to recreate Hagia Sophia’s acoustic signature.
The team also mapped some of Turkey’s grandest mosques, including the massive Süleymaniye, which contains 4677 surfaces and 7123 corners. Modelling the Süleymaniye mosque is seen as particularly important, because the acoustics of this stunning building had been carelessly destroyed by shoddy restoration efforts at some point in the mosque’s history.
In the 16th Century, Mimar Sinan, the master builder of the Ottoman Empire, designed the acoustics of Süleymaniye so that songs, prayers, and recitals would carry throughout the building. He placed jugs into the walls and domes of the mosque, with their openings facing the air, so that sound waves moved through the receptacles in a particular pattern.
But, at some point in the mosque’s history, many of the jugs were accidentally filled with plaster, destroying Sinan’s ground-breaking acoustic work. Christensen’s work has been able to revived Sinan’s designs virtually.
Since resurrecting the sounds of Turkey’s past, Christensen and his team have mapped the acoustics of ancient Greek and Roman theatres. Meanwhile, other groups have used his computer software to map the sounds of Stonehenge.
According to Christensen, these models might not just recreate acoustic history on a computer. “The technique can also be used for evaluating renovations of buildings,” he says. Computer models, for example, allow designers to understand how future restorations could change the sounds of a worship site – before plasterers plug the holes of acoustic history.
(Originally Published in New Scientist Magazine‘s Aus/NZ Travel Section)
For more information:
New Scientist – Sacred echoes
Predicting the Acoustics of Ancient Open Air Theatres