In the northeast of Cairo, in the city of El Shorouk, our partners from MSCC have been tasked with a challenge: the planning and installation of an announcement system with the best possible speech intelligibility at the biggest singular dome in Egypt, the dome of the Al Masjed Al Jami’ Mosque. Given the fact that this dome has a diameter of 32 meters, the inside of the mosque contains of large spaces with mostly hard surfaces, these parameters alone add up to more than one challenge for a public address system. While speech intelligibility was first priority, the customer also wanted to reduce the number of installed speaker to a minimum. MSCC thus worked with TOA’s technical department to plan the installation thoroughly and run simulations to find the perfect solution. This was achieved with TOA’s SR-S4 Slimline Array Speakers and SR-H2 as a backing speakers. line array speakers. To assemble the PA system, the digital mixer M-9000M2 was set up with the power amplifier DA-250 and complemented with an assortment of different microphones to be prepared for every kind of speech, recitation or lecture.