Fancy five 20-tonne slabs of concrete and brick moving over your head? That’s how Fernando Menis controls the acoustics of CKK Jordanki Concert Hall. Story: Mark Davie
Architects must hate it when client’s change their mind. Say the brief was to build a retirement home for a sexagenarian couple — a well-considered, modernist abode with all the mod cons a long service leave payout can buy. The architect goes ahead and designs a smaller, easily maintainable home with only a couple of rooms and plenty of wall space for their pre-war art collection. No one mentioned room for the extended family rocking up on the weekend, or the raucous grandkid sleepovers on Friday nights, until the design was already done. Fernando Menis, principal of Spanishbased firm Fernando Menis Architects, seems to handle those kind of last minute requests well. Menis won a 2008 international ideas competition for the new CKK Jordanki concert hall in Toruń, Poland under the direction it would only be used for symphonic concerts. When the post-competition design process started — the time when sketches are turned into accurate drawings — the city decided it actually wanted more than a home for the Toruń Symphony Orchestra. It wanted to be able to house all manner of theatre, opera, musicals, concerts, even conventions and television shows. Knowing that a static hall could not cope with such a varied program, Menis went back to the drawing board. He is a student of acoustics, specifically as it relates to the behaviour of concrete. It’s been a heavily researched topic around his office over the last 12 years. They call it ‘liquid stone’, because it allows them to define specific geometry via formwork that controls early reflections. Another material Menis has become AT 18
intimately familiar with is ‘picado’, a mixture of concrete and chopped up brick which forms an irregular surface for high frequency diffusion (2kHz and above) that Menis says is “very difficult to achieve with other materials.” It softens the hard specular reflection of hard flat surfaces, smoothing out the sound of orchestral early reflections. He attributes the idea to a ‘rationalised’ [archi-speak] version of what Baroque architects would do with décor and ornamentation. The use of picado was a win-win for the design. The heavy concrete and brick surfaces minimise low frequency absorption to deliver fullness in the low end, but it also fits in well with Toruń’s World Heritage Site-listed red brick Gothic buildings. MLS (Maximum Length Sequence) diffusors have also been integrated in the movable walls to avoid acoustic glare. That would have all been, relatively speaking, putting lipstick on a pig if Menis’s design was still
a standard hall. However, the CKK Jordanki is anything but standard. The subterranean appearance of the hall is reinforced by its asymmetrical geometry, which “contributes to a completely diffuse reverberant field and a good sense of envelopment, making the audience feel surrounded by sound,” said acoustic design engineer Pedro Cerdá of i2A acoustic & Audiovisual Engineering. “Each surface was carefully sized and oriented in order to enhance lateral reflections and provide a strong spatial feeling to the audience.” To do that, they literally built 1/50th-scale clay models, layered the inner surfaces with aluminium foil and shot laser beams into them. They repeated the process eight times, analysing the reflections, then refined the final shape with computer 3D modelling. The main acoustic feat, and what sets CKK
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T30 (s) Ceiling in lower position, acoustic banners deployed T30 (s) Ceiling in upper position, acoustic banners retracted