The possibility of Sir Simon Rattle getting a new concert hall built in London has sparked controversy. Unsurprisingly, there have been arguments about whether the Government should be spending £5.5M to develop a business plan or whether it is reasonable in a time of austerity to be contemplating spending something like £278m on a new auditorium.
More unexpected, there have been the arguments in the press about what shape the concert hall should be. (It seems to me a bit premature to be having such arguments.) Some have been saying it must be a shoe-box: rectangular and tall like the Musikverein in Vienna. Others have been arguing that a new design is needed, something bold like the Philharmonie de Paris with its futuristic curves and radical flying balconies and clouds. So what is the best shape for sound?
The perfect shoe-box? Grosser Musikvereinssaal
The Grosser Musikvereinssaal is usually cited as one of the best concert halls in the World for classical music, and it is a shoe-box shape. But that doesn’t mean an exact replica should be built in London. The Musikverein has capacity of just under 1700. If a replica was built with the modern comfort requirements of half a square metre per seat, then only 1300 people would be able to fit in. This is too small an audience for the new London hall, which needs to have a capacity of around 2000.
How about copying Musikverein but making it a big bigger so enough people can fit in? But that doesn’t mean make it wider, because it is important to have plenty of early reflections arriving at the listener from the side. Numerous scientific studies dating back to the late 1960s have demonstrated the importance of early lateral reflections.
Sound coming straight from the stage gives the same sound at both ears. because the head is symmetrical and so the sound to both ears travel an identical path. When reflections come from the side, the sound at each ear is different. Sound to the furthest ear has to bend around the head. The difference in the sound at the two ear gives a sense of being enveloped by the sound and that improves the music.
Recent work by Jukka Pätynen and collaborators have demonstrated that the crescendos in the Musikverein are particularly impactful because of the strong, high-frequency lateral reflections.
If we can’t make the hall wider, we have to make it taller and longer. If you compare a modern shoebox concert hall like McDermott in Dallas, it is about one and a half times taller than the Musikverein. The problem with making it longer, is the unfortunate people who have to sit right at the back. Symphony Hall Birmingham rightly has a high reputation for its acoustics, but the hall is nearly ten-metres longer than St Davids Hall in Cardiff (a non-shoebox shape). It doesn’t require a scientific study to know that the quality of the experience drops off if you’re too far from the stage, for both visual and acoustic reasons. For this reason, a simple rule of thumb used in design is that the furthest audience member shouldn’t be more than 40 m from the stage .
Consequently, if London was to opt for a simple classic shoebox shaped hall with 2000 seats, in my opinion its hard to see how this design can work unless you make the decision that a certain number of these seats are going to less good because of the distance from the stage. Is there anything wrong with that? After all classic hippodrome theatres have ‘the gods’, the cheap seats, so this is something audiences are used to.
If London does opt for a shoe-box hall, a modern design to copy would be the Culture and Congress Centre Concert Hall, Lucerne, Switzerland (but without the reverberation chambers). I haven’t heard the hall myself, but acoustic engineers I know talk about how good it sounds. Mind you, I think this is an unlikely option, because Lucerne is one a series of halls that were built to almost the same design. The second one in the series was Birmingham Symphony Hall. Where Birmingham leads London follows?!
More on other possible shapes next week.
 Barron, M., 2009. Auditorium acoustics and architectural design. Routledge.