Apparently, much like the multiple orthodox jews in a plane who EACH, before takeoff, have to say a prayer that the plane won't crash (is the guy in 32a better at it than the guy in 34d?), each mosque has to broadcast it's OWN call to prayer at exactly the same time. The resulting cacophany is ear deafening. NB: I never did see anyone stop what they were doing, or rush off somewhere, as a result. Ultimately I found the 4:30 cacophany soothing as well - go figure.