RCF speakers increase clarity at Sulim Kadyrov Mosque

Russia:

The Sulim Kadyrov Mosque, located in the village of Oyskhara, has the capacity to hold up to 15,000 people. A grand opening took place in August 2020, with the head of the Chechen Republic, Ramzan Kadyrov, attending as a special guest. The mosque is named after Sulim Kadyrov who, in 1932, was convicted for teaching the Holy Quran and spent 14 years in the Gulag camps. The installation of over 70 RCF speakers was carried out by Master Sound with the assistance of RCF’s Moscow-based distributor, ARIS.

Since there are no intelligibility standards in Russia, ARIS engineers used external scientific publications about acoustic standards in mosques. Using AFMG EASE modelling software and taking into account the volume of the main prayer hall, it was calculated that the optimum reverberation time for RT60 in the 500Hz – 1kHz frequency range should be 1.9–2.2s. “Since there were no possible adjustments to the original finish, the challenge to reach the optimal RT60 was difficult,” commented Alexandr Shamray, head of sales at ARIS. “To achieve good intelligibility, the Speech Transmission Index must be around 0.60. Taking into account the extremely high resonance of prayer halls and the lack of acoustic absorbers, we focused on intelligibility parameters. Relying solely on controlled directivity and quality of the sound system, we worked on reaching 0.50–0.55 (or higher).

"Focusing on the 250Hz, 500Hz and 1kHz frequency bands, we simulated the results using RCF’s digitally steerable VSA 1250 II and VSA 2050 II columns, placing the loudspeakers, where possible, with a maximum coverage of 10m,” continued Shamray. “These columns have a fairly narrow vertical radiation pattern, which increases the beam of direct sound into the area and reduces the amount of unwanted reflections. This approach is extremely important for increasing speech intelligibility in rooms with high reverberation.”

Four RCF VSA 1250 II speakers are suspended on the front wall near the mihrab (a niche in which the imam is located during the service) and under the gallery, at a height of 2m. Two more VSA 2050 IIs are suspended on a pair of columns supporting the dome closest to the mihrab, also at a height of 2m. An additional pair of RCF VSA 1250 IIs provide the delay, suspended on a pair of columns supporting the dome, farthest from the mihrab, again at a height of 2m. Ten RCF L 2406T sound columns are used as sound systems for the balcony, placed on the front wall and on the balcony column. Finally, 44 PL 8X ceiling loudspeakers have been installed in both the prayer halls on the basement level.

The tradition of inviting people to pray at the mosque with a singing voice has been used by Muslims for 14 centuries. It was therefore necessary to amplify the voice of the muezzin so that it can heard over the noise of a modern city. As a result, each minaret is equipped with four weatherproof RCF HD 410T and HD 6045EN horn-type speakers and used for the daily calls to prayer (adhān and ṣalāt).

Shamray was pleased to report that all measurements fell within 96% of the calculations, resulting in a non-tiring and intelligible sound system with good performance and perfect coverage.