The opening of any new concert hall has journalists and musicians reflecting on this question and last week’s opening of the Danish Radio Concert Hall in Copenhagen was no exception. Preference for acoustics is often a matter of taste, and much like wine, these tastes can vary from person to person.Objective measurements by acousticians allow subjective preferences to be compared to objective measurements. Leo Beranek makes this comparison for 100 halls in his book Concert Halls and Opera Houses, Music, Architecture and Acoustics and also recently updated published papers.
There is a direct relationship between architecture and acoustics that relates to the physical properties of sound. The speed of sound is a constant in air (approx 340 m/s). Human hearing is in the frequency range from 20 Hz to 20,000 Hz, corresponding to wavelengths of sound from 17m to 0.017m. The physical dimensions of a space, and the relationship of the surface locations, texture and material depth between the orchestra and listener will govern how one hears the sound reflections. In very simple terms, when listening in a concert hall, we hear sound in 3 components:
Direct sound – the sound that comes straight to our ears from the orchestra
Early reflections – the sounds we hear that reflect from surfaces in the hall before they reach our earsStudies indicate that good early lateral (side) reflections within approximately 80ms of the direct sound are crucial for good spatial impression
Reverberation – the exponential decay of multiple sound reflections
These components influence:
Loudness – simply how loud the orchestra sounds
Clarity – the ability to make out fast moving melody within the overall reverberation in the room
Intimacy – how close you feel to the music and musicians
Envelopment – the feeling of the music surrounding you – being immersed in the sound
The hall shape, length, width, height and material geometry will dictate the balance between these three components, and the preference varies from person to person.
Aural intimacy is different to visual intimacy; it is governed by how quickly you hear the first reflections in the room. So a small window of time between direct sound and first reflections makes you feel closer to the performers, which is part of the success of the most famous halls in the world.
So what are the types of hall and how do they sound?
“Shoebox” concert halls. Perhaps the most famous concert hall form exemplified by the Grosser Musikverinsaal (Vienna) and Concertgebouw (Amsterdam). These two late 19th century rooms are a culmination of many hundreds of years of concert hall design. They have approximately 1650 seats and 2000 seats respectively.
The audience is arranged progressively further from the orchestra platform, in a narrow rectangular plan. The floor is relatively flat exposing the mostly sound reflecting sidewalls to the audience ensuring strong lateral reflections to listeners. The rear wall is exposed so the sound can reflect back to provide enveloping reflections. There is generally one narrow balcony to provide “cue-ball” reflections to reinforce room height. The upper two thirds of the room are generally sound diffusing with increasing surface modulation with height – this modulation varies in size to ensure sound is diffused over a wide frequency range. This upper volume creates the warmer richer reverberance. These conditions create a rich, intimate and enveloping sound, with uniformity of acoustical excellence throughout the room.
The shoebox has proved successful in achieving acoustical excellence and has been copied and modified by many throughout the 20th and early 21st centuries. In Beranek’s book, of the 20 top halls in the world, the majority are shoebox concert halls. And recently built modern halls, such has The Sage Gateshead Hall 1, have been similarly successful in achieving acoustical excellence.
“Large Shoebox” Halls. While retaining the basic form of the famed halls, additional changes are made primarily to increase the overall seat count above 2000 seats. Boston Symphony Hall ranks alongside the Vienna and Amsterdam halls as one of the worlds greatest and has similar features to those halls adding a second tier to increase the seat count (it was also built in 1900).
Other more modern examples built in the post war era have a number of features that can be detrimental to acoustics. Raked floors improve sightlines but reduce lateral and rear enveloping reflections and reduce strength of sound. Multiple balconies stacked up on the sides reduce the development of reverberance and overhangs can limit the exposure of seats to sound from the upper room volume. These features change the relationship of direct to early reflections to reverberance, and hence the richness of the original shoebox halls.
Vineyard Halls. Made famous by Hans Scharoun for the Berlin Philharmonie. The style breaks the seating into blocks and surrounds the stage. The form often uses walls around the seating blocks to deliver early reflections, but the balance is different to that of the shoebox. In front of the orchestra platform, the vineyard can provide opportunity for good clear direct sound balanced with reverberance from the upper room volume. The advantages are close visual proximity of the audience to the orchestra (although some have more limited views than in a shoebox) and some people enjoy the feeling of almost being seated with the players.
The criticisms are that to the rear or near-rear of the stage the balance of the orchestral sound can be widely variable - this is because the sound of the instruments primarily radiates forwards. The lateral reflections and envelopment from the shoebox halls is generally not achieved because of the geometry.
There are 3 vineyard rooms in Beranek’s top 20 rankings; Berlin, Suntory (Tokyo) and St David’s Hall (Cardiff).
Hybrid Halls. Examples of this architectural style include Walt Disney Concert Hall (Los Angeles), Boettcher Hall (Denver) and Christchurch Town Hall (New Zealand). Leo Beranek’s observations of the sound in Disney Hall is summarized in his recent paper.
He poses an interesting question – are contemporary hall styles better suited to contemporary music?
Architecture is Acoustics, Acoustics is Architecture. Room shape, form, geometry and materials are vital in achieving acoustical success in any performing arts space. Great architecture is essential to make performing arts spaces exciting for current and future generations. The collaboration between acoustician and architect is fundamental in achieving these goals. The tools available in this process are rapidly expanding. Using a process called “Auralization” designers can listen to buildings before they are built. Arup Acoustics is at the forefront of this pioneering work and their Arup SoundLab has already been successfully used to work collaboratively with architects in designing exciting performing arts spaces. It can be used to actively push the boundaries of architecture while still achieving acoustical excellence. So waiting in suspense to test the acoustics of a concert hall on opening day should be a thing of the past.
Technology continues to penetrate all aspects of our lives and the concert hall is no exception. Many concert halls no longer serve the single function as a home for an orchestra. They need to be capable of accommodating a wide range of performance types and collaborations between orchestras, electronic music and instruments and multi-media visual art. This requires technology to vary the acoustics and support electro-acoustics and multimedia visual equipment. The future success of concert halls will be dependant on generating new audiences - encouraging future generations of audience and donors to come and interact with the building.
The surround hall has seen renewed interest in recent years, perhaps for these reasons. On a smaller scale, The Sage Gateshead Hall 2, designed by Foster and Partners with Arup Acoustics was conceived as a near circular room, with the expectation of immersive sound experiences and a space for work to be created and performed, which it has been successful in achieving. As well as the new Danish Radio Concert Hall, the new Paris Concert Hall and Concert Hall in Hamburg are both conceived in a similar form for 2500 seats:
In this context, the ingredients that would make up the “best concert hall in the world” depend much on what the future of music composition and performance will become. As yet, this future is unwritten. But the technology to ensure design success is here now and ready to be embraced.
Michael Hammond is author of Performing Architecture published by Merrell.
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