Acoustics: perfecting the science of sound for Berlin’s Pierre Boulez Saal concert hall
Image credit: Volker Kreidler
From concert halls to video games, acoustics is an interdisciplinary science encompassing a wide range of topics for engineers and technologists to get their ears and finely tuned brains around.
Berlin has a new concert hall: the Pierre Boulez Saal opened last month and is a single-room facility with seating for 620, located in the cultural heart of the city. It is designed as a modular 360-degree elliptical space in which musicians and concert-goers can be moved around without impacting upon the acoustic quality and the enjoyment of all those pairs of ears.
The Pierre Boulez Saal has been designed by American architect Frank Gehry, the classical music-loving architect behind the Walt Disney Concert Hall in Los Angeles. For the project, which took four years to build, Gehry teamed up again with his Disney collaborator Yasuhisa Toyota, the renowned Japanese acoustician, both of them waiving their fees to work on the project.
Yasuhisa Toyota, an engineer, is behind some of the world’s most celebrated concert halls and his expertise is sought around the world as classical music venues are increasingly designed in ‘vineyard style’. Like the Pierre Boulez Saal, this is where audiences surround the stage, rising up in serried rows - like the sloping terraces of a vineyard - in order to hear the performers up close and enjoy an almost-interactive experience. It contrasts with the shoebox style, which has a rectangular auditorium and a stage at one end, fan-shaped, such as that at London’s Barbican, or an arena, as at the Royal Albert Hall.
Toyota is president and founder of Nagata Acoustics America and has been chief acoustician for over 50 projects worldwide, including the Walt Disney Concert Hall, Suntory Hall in Tokyo, the Bard College Performing Arts Center in New York, the Elbphilharmonie in Hamburg and the Kauffman Center for the Performing Arts in Kansas City.
The Pierre-Boulez-Saal has been created as a new function within an existing, historic structure, designed by architect Richard Paulick in the 1950s to store sets for the Berlin State Opera. As such, the existing building defines the overall available space for the hall, some 25m square and 14m tall, and calls for a unique vision of a flexible layout in order to accommodate all of the necessary requirements.
The concert hall is a part of the Barenboim-Said Academy, created in the spirit of the West-Eastern Divan Orchestra. Established in 1999 by Daniel Barenboim and the late American-Palestinian literary scholar Edward W. Said, its goal was to bring together, as equals, young Arab and Israeli musicians and began its teaching programme in autumn 2016.
Gehry’s innovative design organises the seating in an oval shape around the performers in the centre of the square room. A dramatic oval balcony with two rows floats above the audience and is rotated gently against the oval shape of the seating below. The balcony is apparently supported only by four slender columns, in addition to touching the main walls of the room near the mid-point of each wall, allowing the corners behind the balcony to merge with the main volume of the space. The most dramatic element of the balcony is the gentle rising and falling of the floor level around the room: in the course of walking all the way around the balcony, a person will have risen and fallen by roughly one metre.
In order to accommodate the 620 planned audience seats, as well as the space for large orchestra rehearsal, a highly flexible seating layout was developed. At the centre of the room, on the same level as the musicians, there are three rows of loose seats. Then, four rows of seats are installed on retractable risers. Finally, at the level of the audience entry, one fixed row of bench seating is installed as the last row of seating surrounding the stage. Together with the balcony above, the loose seats and retractable risers offer many different performance configurations.
Toyota’s acoustical design of the hall is focused on providing a space for full orchestra rehearsal within a concert hall for chamber music. The most important design direction to accommodate a full orchestra is to keep enough ceiling height above the stage.
Since the project is the renovation of an existing building, there were many restrictions. The final result places the stage at the bottom of the building so that Toyota could make the most use of the existing structure. Thus the entire volume is used acoustically. The overall shape of the hall is a typical shoebox and the best direction of acoustical design was to use this basic shape. To keep the strong benefits of the shoebox style, the aim was to design the floating balcony with the greatest possible acoustical transparency. The guard rail in front of the audience is made of thin pipes, in order to keep maximal transparency. In addition, the overall structure of the balcony was designed to be acoustically transparent, resulting in the concrete truss punctuated with many large holes.
To ensure the best possible sound quality, the floor slabs and sheer walls of the existing building have been removed, with only the façade and roof maintained. Panels of Douglas fir line the walls and ceiling and on the east and south sides, four bays of three windows each connect the hall visually to the surrounding neighbourhood, with the intention of making “the space feel like a room in the city, with an interior that reflects the Berlin sky”.
Flexibility and intimacy are central to the design, with the audience surrounding the musicians on all sides. The maximum distance between the conductor and the farthest seat is around 14m. There are two column-free sloping balconies on the upper level, which are rotated slightly against the axis of the oval stage to enhance sight lines.
Describing his design, Gehry said: “It feels like a connection to the city, which is right because this is not an exterior concert hall like the Philharmonic or Disney Hall. It’s part of the city because the interior of the old building has history and has memories and there is something about that that appeals to me.”
So, how does an acoustician approach a project like this? Just how good do their ears have to be? The quality of sound is determined by the characteristics, grade, location and shape of any given room. The ideal sound environment, whether that’s for a concert hall, school gym, recording studio, or other facility, fundamentally depends on three variables: room acoustics, sound system and quietness.
According to Nagata Acoustics, a typical project tends to follow a set plan involving a programming stage at the outset where the acoustical goal is outlined, followed by schematic design and design development phases involving room-shape computer simulations with calculations of acoustical parameters and a check of building materials and structures, followed by experiments using scale models.
During the construction phase of a project, the acoustician conducts on-site inspections, working with the architect, engineer and theatre consultant in drafting and finalising construction documents, and supervising implementation of acoustical design and noise controls.
No project is considered completed until it is tested in real-use situations and the acoustics are fine-tuned. In addition to using instrument measurement, Nagata acousticians listen to critiques from the client and performers, adjusting the acoustics to maximize perceived satisfaction as well as meet statistical goals.
As mentioned earlier, a career in acoustics encompasses a number of disciplines. The so called ‘Lindsay's Wheel of Acoustics’, created by Robert Bruce Lindsay in 1964 is a well-accepted overview of the various fields in acoustics and describes the field’s scope starting from the four broad fields of Earth sciences, engineering, life sciences, and the arts.
In the Acoustics and Audio Group at Scotland’s University of Edinburgh, the MSc in Acoustics and Music Technology (AMT) programme is designed to allow students to develop both technical knowledge and practical experience of acoustics and musical technology. Here, Stephen Oxnard, AMT MSc alumnus, describes his experience:
“My first venture into the subject of acoustics took place during undergraduate studies in electronics with music technology systems at the University of York. I took part in a project that sought to sonically revive a 14th-century Abbey using virtual acoustic modelling techniques.
“The AMT course at Edinburgh provided a perfect opportunity to learn the underlying principles and practices of acoustics from renowned experts in the field. Throughout the course, fundamental theory could be applied in practise in various contexts including physical modelling, sound design and digital media ensuring that a very high level of understanding was attainable.
“Upon completion of the course, I found that I was in a great position to further my studies into aspects of virtual acoustics that I was exposed to during the MSc. To this end I started a PhD in the Audio Lab at the University of York.”
Another alumnus of the course, Benoit Alary, says: “I went into the master’s course following a few years in the video game industry where I specialised in audio technologies development. Having a BSc in computer sciences, but no formal training in audio, I quickly realised that further studies would be crucial to carry out work in this field.
“The MSc programme at Edinburgh University really stood out to me. Having a relevant acoustics and signal processing curriculum, along with an interesting emphasis on physical modelling sound synthesis, the programme provides a strong scientific basis. It can also be tailored to accommodate a variety of backgrounds and interests, which includes practical courses in sound design and graduate classes in computer sciences. Since graduation, I’ve been working for one of the leading audio technology companies in the video game industry.
“It’s an exciting time for audio technologies, with emerging computing capabilities and interfaces opening new realms of possibilities for interactive sounds like never before.”