Adjustable acoustics and musician adaptation at the concert hall in Aalborg, Denmark.

Abstract

The concert hall at the Musikkenshus (House of Music) in Aalborg, Denmark, was opened in 2014. The architect, Wolf D. Prix of Coop Himmelb(l)au in Vienna was selected through a competitive process while Artec Consultants Inc. (Artec) was selected to be the acoustics consultant and theater designer1 through a parallel process. The architectural concept places the 1,300-seat concert hall at the center of a notional courtyard, with three levels of rehearsal, practice, teaching and support spaces surrounding on three sides. The facility is resident to three local organizations-the Aalborg Symphony Orchestra, the Royal Conservatory, and the music department of the Aalborg University- and is managed by an eponymous organization founded for the purpose.The acoustics and theater consultant was hired by a knowledgeable client on the premise that this concert hall should fit in with the quality level that defines the family of internationally recognized music spaces that this firm had developed under Russell Johnson's leadership. Many of these halls, including the Kulturund Kongresszentrum Luzern (Switzerland), Sibeliustalo in Lahti (Finland), Sala Sao Paolo (Brazil), Bartok Concert Hall in Budapest (Hungary), and Esplanade Concert Hall (Singapore) feature significant adjustable acoustics elements, including large and heavy multipiece canopies (reflectors) primarily above the stage, secondary coupled-volume acoustic and sound absorptive cloth systems. The client specifically indicated that this project, within the limits of the construction budget, should include such systems as necessary to achieve a quality acoustic environment for the entire range of expected usage.The design was developed also in specific response to discussions with the client, the size of the Aalborg Symphony Orchestra- typically 76 musicians but with a Mahler or similarly large (no more than 110 musicians) instrumentation orchestral performance once or twice every season-and the desire to incorporate a pipe organ under a constrained budget.Acoustical Design IntentA fundamental shift in acoustical design approach took place at Artec during the period between 2003 and 2008. During this period, listening experiences in Lucerne, Switzerland; Singapore; and Budapest, in particular, led to thinking that we should consider these concert halls as a single volume with adjustable panels dispersed within it, allowing users to variably couple volumes within that single space rather than thinking of a main concert chamber with add-on secondary volumes. This fundamental change was then applied to the design of multipiece canopies, resulting in generally greater coverage over the stage platform and a greater number of individually adjustable segments than had previously been designed by the acoustics and theater consultant. The intent was to provide acoustic coupling previously achieved through chambers via apertures between the individual canopy elements. The intent behind greater coverage was to provide greater flexibility in adjusting the openings while also providing the necessary support on stage.At the same time, access to this significant body of work with consistent design features led to the recognition that one of the main attributes that have made Artec rooms so popular with artists and audiences is an acoustical signature that has proven remarkably constant and recognizable to musicians and lay listeners, despite the obvious fact that each room has its own independent character. Musicians who perform in Artec's halls have described this signature as having a high level of perceived reverberance combined with a level of perceived clarity. Artec's designers determined that the incorporation of variably coupled volumes within the auditorium design is a key part of creating that sound signature by affecting the relationship between early and late parts of the acoustic decay. Experience in these halls has also led us to understand that the panels separating these volumes must be exceptionally massive with surface densities of 70 kg/m2 or higher to avoid the loss of warmth in low frequencies. …