Opera house roof gets special soundcheck

One million brilliant white tiles clad the 65m-tall precast concrete roof of the 43-year-old Sydney Opera HouseJrn Utzons Modernist tour de force overlooking the Australian citys harbour. The glazed ceramic tiles need to be hand-checked, or tapped, every five years by specialist engineers, who abseil down the roof sails looking for changes in their sound or appearance. Now, thanks to the combined efforts of the opera house, the Getty Foundation, the University of Sydney and the engineering and