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Doha, Qatar | June, 2011 – With a surface area of almost 20,000 square metres over three levels, and a capacity for 30,000 worshippers, the State Mosque in Al Khuwair, Doha, is billed as Qatar’s largest religious edifice.
Its lavish and spectacular architecture incorporates traditional Islamic elements, including numerous domes. The main prayer hall, with a capacity for 1,300 worshippers, has 28 large domes, in addition to the 65 minor domes around the perimeter, and a 65ft-high single minaret.
Being constructed almost entirely in materials with hard surfaces, such as marble and glass, meant that like many mosques, Qatar provided a major acoustical challenge, in particular long reverberation times. Extra special attention was required in choosing the sound system for such a demanding building.
AV-TECH, one of the region’s leading suppliers of high-end audio, video, broadcast and lighting equipment, was brought in for its experience in dealing with many similar projects, and its reputation for designing leading-edge live performance systems.
The company’s general manager, Hadi Arzouni, felt that maintaining the architectural consistency of the mosque was the main challenge. “The requirement was that the installed sound system should not affect the architecture of the mosque, and should use the most appropriate speaker system, ensuring that the sound intelligibility would be at its best,” he says.
To help them meet the challenge involved in this vast project, AV-TECH brought in Swedish audio consultants, Soliflex, to carry out the EASE analysis for the system design in the main prayer hall.
As soon as he visited the site, Soliflex’s senior advisor Jan Setterberg saw what would be their biggest challenge: “I could see we were up against an enormous reverberation time here – the calculation gave a result peaking at around 9 seconds. We told them that with this reverb time, almost every loudspeaker on the planet would struggle to be heard.”
Added to this the EASE simulations had a very low speech transmission index; there was no acoustic dampening treatment on the walls; and the speakers were placed too low. “The column speakers were shooting at around 6.5m above the heads of the audience. I explained that if they wanted intelligible sound, they would have to redesign the whole system.”
ACOUSTICS UNDER CONTROL
First it was necessary to get the acoustics under control – a job that involved importing thousands of square metres of a special acoustic plaster from Fellert in Sweden, with the result that the RT was reduced to around five seconds, essential in a venue where the loudspeakers are used almost exclusively for speech. “I couldn’t do anything about the low end, but I was able to get it under control in the frequencies of the spoken word,” says Setterberg.
Next up was to design the sound system itself, with speakers that would work specifically with the acoustic treatment. Enter the Renkus-Heinz Iconyx system, selected not only for its unparalleled clarity, but also its facility for adjustment according to the number of worshippers as well as the characteristics of the speaker’s voice.
Says Setterberg, “For this project, I wanted something I felt safe with. We also needed column speakers with beam-steering capabilities to direct the sound where it’s needed – for example, when worshippers are in the kneeling position, the hearing point is just 1.2 metres above ground. We have one beam that is tilted as much as possible, to cover the front, and that’s attenuated by a couple of dBs to even out the sound.
“We used six IC24-R columns at the front wall, six IC8-Rs to be like a delay system at the back, plus six IC8-Rs in the ladies’ prayer hall. This is connected to the main prayer hall but you can’t get any direct sound from the IC24 system up there, so we installed IC8-Rs there as well.”
The 120m-long marble corridor that runs behind the back of the main prayer hall is covered by another six IC8-Rs, while the space under the mezzanine also has six IC8-Rs. In keeping with the brief to make the system as discreet as possible, most of the loudspeakers are installed in recesses in the columns, behind ornate gold grilles.
Outside in the large courtyard, four weather-proof high-capacity IC Live speakers were installed, chosen for their tight pattern control – essential for delivering intelligible speech in an open but highly reflective area such as this.
The whole system is controlled by a Yamaha DME64, which allows different zones to be switched on and off. Says Setterberg: “We put in some presets for equalization – for when, say, the hall is only half full.” He continues, “The speaker processing and delay is handled by the Renkus-Heinz RHAON network. We use CobraNet for the signal distribution, and we also have analogue backup.”
WORTH THE WAIT
As you would expect for a project of this magnitude, the installation took 18 months to complete. And the verdict? Says Harish Kunju of AV-TECH: “The contractor and the electro-mechanical company did a great job. We all worked as a team together with the consultant. At the end of the day it is a mosque, a special building.”
Jan Setterberg concludes: “I’m very pleased with the quality. It’s been an exciting and very different job for me.”
A project such as the Qatar State Mosque shows that no matter how acoustically challenged a building, with the right equipment – and perhaps a prayer or two – it can be done, even if you have to move heaven and earth to achieve it.