Proceedings of the Institute of Acoustics

ACOUSTICAL DESIGN OF

K Oguchi Nagata Acoustics M Quiquerez Nagata Acoustics Y Toyota Nagata Acoustics

1 INTRODUCTION

In ’s second largest city, , the new concert hall venue Elbphilharmonie opened on January 11, 2017. Historically, the city of Hamburg developed as a port and commercial city on the River that connects the port to the North Sea. Facing directly to the Elbe River, in a district where old warehouses faced the river and that has become one of the most significant parts of the city, the new cultural landmark, Elbphilharmonie was inaugurated.

This paper reports on the acoustical design and characteristics of the Grosser Saal.

2 PROJECT OVERVIEW

The Elbphilharmonie stands prominently on a 1963 warehouse surrounded on three sides by Elbe River. The building that houses Elbphilharmonie has 26 stories and a gross floor area of approximately 125,000 m2. The building comprises a 2,100-seat "Grosser Saal" (Large Hall), a 550-seat "Kleiner Saal" (Small Hall) and ancillary spaces, as well as a hotel and condominiums.

The Grosser Saal is designed as a concert hall for classical music, and the Kleiner Saal is designed as a multipurpose hall with the focus primarily on chamber music and secondarily for a wide range of performances and events such as popular music genres, drama and lectures.

At the eighth floor, the building offers incredible 360-degree vistas of the city and the Elbe River. On this level, a Plaza offers access to the general public and also serves as the entrance to the Grosser Saal and Kleiner Saal built on the floors above the Plaza. The arrangement of the facilities is shown in Figure 1 and the venue data is summarized in Table 1.

Elbphilharmonie is operated by HamburgMusik gGmbH – Elbphilharmonie und . The resident orchestra in the Grosser Saal is NDR Elbphilharmonie Orchestra, using the stage on a daily basis to rehearse and also presenting subscription concerts. is Ensemble in Residence of the Kleiner Saal.

The Swiss architectural firm of Herzog & de Meuron created the Elbphilharmonie’s architectural design. AG served as the general contractor. Nagata Acoustics provided all acoustical consulting services for the Grosser Saal and Kleiner Saal from the design phase through construction and project completion. Hamburg-based Taubert und Ruhe GmbH provided building acoustics services for the remainder of the building.

3 ACOUSTICAL DESIGN OF GROSSER SAAL

The room acoustic design of concert halls might be summarized as two important issues, the “room shape” and the “interior finish materials”. Of course, consideration of the room shape includes the overall seating layout, both the major elements of ceiling height and room width, and also details such as surface textures along the ceiling and walls. The interior finish materials include not only the surface materials, but also the properties of the structure which support them. The room acoustic design must address all of these matters, but it is also true that the same matters are the focus of the

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architectural design. Architects and acousticians, therefore, need to collaborate closely as a team to design an excellent concert hall.

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Figure 1 - Elbphilharmonie (Quoted from Elbphilharmonie Website)

Table 1 - Venue data of Elbphilharmonie Location Platz der Deutschen Einheit 1-5, Hamburg, Germany Client Freie und Hansestadt Hamburg, Germany Architect Herzog & de Meuron Construction Hochtief AG HamburgMusik gGmbH Operation – Elbphilharmonie und Laeiszhalle Year opened 2017 Resident NDR Elbphilharmonie Orchestra Ensemble Ensemble Resonanz

Gross floor area 125,512 m2 Cost 789 million EUR (entire building) 1. Grosser Saal, 2. Kleiner Saal, Facilities 3. Hotel, 4. Residences, 5. Plaza

The design keyword of the Grosser Saal is "intimacy". From both the architectural (that is, visual) perspective and the acoustical perspective, intimacy was the aim. Because of the size of Grosser Saal, the question of how to make the audience feel “not distant” from the performers became the most important theme of design work. When Nagata Acoustics joined the project design team, the project had already decided that the basic shape of Grosser Saal would not be the “shoebox” configuration, but instead would use the so-called “vineyard” configuration to seat the audience as close to the stage as possible.

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3.1 Hall shape

Achieving acoustical intimacy predominantly meant how to obtain effective early reflections, that is, how to create acoustically effective walls around and in the vicinities of the sections of audience seating.

The study of the hall shape was conducted with ray-tracing based computer modelling1, followed by acoustical experiments with a 1:10 physical scale model 2. In the computer model, the basic hall shape and dimensions were studied in terms of early reflections. The detrimental echo detections and redesign of the shape to eliminate them were primarily carried out with the physical model experiments, as well as comparison studies of REC curves 3 to other concert halls with excellent acoustics to confirm the acoustics of new halls would be physically excellent. The acoustical experiments with the 1:10 physical scale model are described in the related paper 4. Figure 2 shows the plan of Grosser Saal and Figure 3 shows the section of the entire Elbphilharmonie building. Table 2 shows the architectural data of Grosser Saal.

(1) The hall spans approximately 40 m, and is approximately 50 m long. Maximum distance from conductor is 30 m. (2) In order to achieve acoustical intimacy, the design solution involved creating small groups of audience seats and designing effective, sound-reflecting wall surfaces for every group of audience seating. (3) The highest point of the ceiling is approximately 25 m from the stage level to keep enough room air volume. (4) An orchestra canopy is suspended above the stage to provide necessary reflections to the musicians on the stage and the audience around the stage area. The canopy is a saucer shape of 15 m diameter suspended from the ceiling whose height is fixed at 15 m above the stage.

3.2 Stage

The stage was designed to accommodate a full orchestra and chorus with the dimensions of approximately 21 m wide (at the front) and approximately 15.5 m deep.

Motorized orchestra risers are installed to arrange the orchestras three dimensionally. The core of string instruments sits on the fixed stage floor at center while surrounding strings, wind instruments, and percussions are on the 21 risers, with chorus on 10 risers. The vertical small walls of each risers’ step help to provide early reflections to the players.

3.3 Interior finish

Entering the Elbphilharmonie Grosser Saal from the dynamically flowing and smooth lines of the lobby’s interior surfaces, the eye’s first impression is the sudden change to a room of intentionally uneven, textured wall and ceiling surfaces. The interior finishes in the hall are acoustically reflective, as shown in Table 2.

Wall and Ceiling The seashell motif irregularity was conceived by the architects to act as an acoustic diffusing surface texture, and was also used to eliminate the detrimental echoes. In halls such as Grosser Saal that have the vineyard shape, sound can easily return back onto the stage and audience as a long path echo. In the case of a long path echo, the options to eliminate it are: changing the angles of some reflective surfaces, adding absorption elements, or adding diffuse elements. The architects favoured diffusion to eliminate the long path echo. In order to test and confirm the efficacy of the seashell motif surface, an audition tests were conducted in the model with a 1:10 scale version of the seashell motif affixed to the portions of the wall that had caused the echoes. The diffusive material was fabricated from some layers of high-density gypsum fiberboard with the density of 1,500kg/m3 In the locations where the surface producing soft reflections expected, the depth of irregularity measures 10 to 30 mm. Where the aim is to eliminate echoes, the depth of

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irregularity measures 50 to 90 mm (Figure 4). Also, since these panels must have sufficient weight to effectively reflect sound even at low frequencies, the panels were fabricated so that they have a post- sculpting average density of 125 kg/m2.

The seashell motif is used entirely on the walls and ceiling of the Grosser Saal. The 3D modelling was used to determine where to place joints in the panels and then the panels were fabricated at an off-site factory. The panel joints were caulked with elastic sealant.

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Elbphilharmonie LEVEL 16 Hamburg scale 1:500 N 1 Main Concert Hall 0 5 10m 2 Organ 3 Foyer 4 Residential 5 Hotel 6 Void hotel

Figure 2 - Plan Level 16 (© Herzog & de Meuron)

Elbphilharmonie Hamburg Section

1 Main entrance 2 Parking 3 Performance spaces “Kaistudios” 4 Restaurant 5 Lookout 6 Plaza 7 Void Plaza 8 Chamber 9 Foyer 10 Main Concert Hall 11 Canopy 17 12 Air intake unit 13 Construction space 16 14 Hotel 13 12 15 Void hotel 16 Residential 17 Void residential

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SECTION 1 scale 1:700

0 5 10m Figure 3 - Section (© Herzog & de Meuron) Vol. 38. Pt. 3. 2016

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Table 2 - Architectural data of Concert Hall Seating Capacity 2,100 Room Volume 23,000 m3 Surface Area 8,500 m2 Stage Area 270 m2 Finish Materials Ceiling HGF, milled SMI (Mass 125 kg/m2) Wall HGF, milled SMI (Mass 125 kg/m2) Audi. Floor Wood flooring on HGF Oregon pine 50 mm Stage Floor supported with wooden joists and sleepers Canopy HGF, milled SMI (Mass 125 kg/m2) Seats Upholstered 4-manual, 65 stops Pipe Organ: Johannes HGF: High-density gypsum fiberboard panel SMI: Seashell motif irregularity

Irregularity on orchestra canopy Irregularity for echo elimination Figure 4 - Seashell motif irregularity finish

Audience seat Our primary requirement for the audience seat specified that all surfaces be acoustically reflective except those that would be covered when a person is in the seat. This meant cushioning and upholstering only the front of the seat back and the seat surface, and using wood panelling for the rear side of the seat back. The unique design of the seating creates a visually smooth transition line between the seat and seat back when the seat is in the raised position. The upholstered fabric is attached directly to the rigid panel of the rear side.

In particular, because the seat cushions are thick, its equivalent absorption area (EAA) per seat showed a rather large value of approximately 0.3 at mid frequencies. However, when occupied, EAA measured less than 0.4, which means that the difference between an unoccupied and occupied seating is quite small. Figure 5 shows the absorption characteristics of the Grosser Saal seat.

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Audience seat

Seat arraignment in Grosser Saal Figure 5 - Audience seat and absorption performance

3.4 ROOM ACOUSTICAL PARAMETERS OF GROSSER SAAL

Impulse responses were measured at several points in the Grosser Saal when completed. Some acoustical parameters including those from ISO3382 are derived from the impulse responses. Figure 6 shows the reverberation times (RT60). RT60 at 500Hz measures 2.5 sec in the unoccupied condition, and RT60 when fully occupied is estimated 2.3sec. The retractable acoustical banners are installed behind the audience seats, and the grill of upstage which are raised up or pulled out to create acoustically damped condition for non-classical performances, such as pop music. RT60 unoccupied with the banners deployed is measured to be 2.1 sec. Other room acoustical parameters Strength G, Early decay time EDT, Clarity (C80), and Center Time TS averaged over 37 measuring points in the audience are shown in Table 3.

Table 3 - Room acoustics parameters of Grosser Saal FREQ. [HZ] 125 250 500 1K 2K 4K RT(unocc.)[s] 2.4 2.6 2.5 2.3 2.1 1.9 (occ.)[s] 2.3 2.3 2.3 2.2 2.1 1.8 EDT[s] 2.6 2.6 2.3 2.2 2.0 1.7 C80[dB] 2.6 1.3 0.1 0.4 0.7 1.2 G[dB] 5.3 4.5 6.2 4.6 5.7 6.1 Tc [ms] 190 171 138 132 120 108

Figure 6 - Reverberation time of Grosser Saal

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4 SOUND ISOLATION TO ADDRESS SHIP WHISTLES

Both performance halls are acoustically isolated with steel springs from the loud ship whistle outside at the adjacent port and from the rest of the building. The architects kept the old brick warehouse facade that stands directly at the water’s edge of the Elbe River and constructed the new halls on top of the old facade. The Elbe River functions as an active seaport for large, ocean-going vessels and ship terminals line the waterway on the east side of the Elbphilharmonie building. The berths accommodate large ships such as the Queen Mary 2 (weighing 76,000 tons) and other cruise liners.

When a cruise liner leaves its berth for a voyage, it blows its ship whistle. The sound of the whistle can be heard even several kilometers away in downtown Hamburg hotel rooms. Ship regulations require that the larger the ship, the lower the frequency of the ship’s whistle. In the case of the ship whistle of the Queen Mary 2, sound isolation of ISO R’w of 90, and 75 dB isolation at 125 Hz octave band should be realized under the background noise target of NC-15. To achieve this high level of sound isolation, a building isolation system using metal springs was adopted that can be set to a low natural frequency of less than 5Hz. Both halls have a structure of 200 mm-thick concrete outer box (made of half-precast concrete) and, inside of this box, an inner concrete box also 200 mm-thick (a shotcrete deck structure) is supported on the metal springs. The interior of the halls was constructed inside this inner box concrete structure. The natural frequency of the building isolation system was set at 3.5 Hz for both halls. Figure 7 on the right shows the metal springs at the top of the Grosser Saal with which the inner concrete box is suspended.

In July 2016, the sound isolation solution was tested by measuring and listening to a large ship’s whistle. The whistle could be heard in the space between the outer concrete box and the inner box. However, the ship whistle could not be heard next to the small window facing to the river in the Grosser Saal.

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6 : Outer concrete shell : Inner concrete shell Figure 7 - Acoustical isolation for Grosser Saal

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5 OPENING SERIES AT GROSSER SAAL

On January 11, 2017, the Grosser Saal celebrated its opening after several months’ preparation including rehearsals by the resident orchestras. These rehearsals were important for the resident performers to get used to the new acoustics on the stage.

The opening concert started with the NDR Elbphilharmonie Orchestra performing Beethoven’s overture “Die Geschöpfe des Prometheus” conducted by Maestro Thomas Hengelbrock, followed by a variety of artists performing not only on the stage but also among the audience. A series of orchestra concerts followed after opening night including by some of the most renowned orchestras in the world: Chicago Symphony, Vienna Philharmonic, Berliner Philharmonic, and many others. The music sounded intimate, rich, and clear in the Grosser Saal as intended.

6 REFERENCES

1. K. Oguchi, “Ray tracing simulation technique regarding distribution of early reflections for studying the fundamental room shape of auditoriums”, Proceedings of 14th ICA in (1992). 2. K. Oguchi, “Miniature Loudspeaker for Acoustical Scale Model Test”, Proceedings of International Symposium on Room Acoustics, Seville, 10-12 September (2007). 3. Y. Toyota, K. Oguchi & M. Nagata, “A study on the characteristics of early reflections in concert halls,” Proc. ASA & ASJ 2nd Joint Meeting (1988) 4. M. Quiquerez, K. Oguchi, M. Komoda, D. Beckmann, Y. Toyota, “Acoustics tests with 1:10- scale model: Elbphilharmonie case study, Proceedings of Acoustics 2018 in Hamburg (2018)

Exterior View from North Interior View

Ceiling and Orchestra Canopy Acoustic Banner

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