The acoustic requirements for opera and for musical theatre are very different. So how do you accommodate both in the same space?
Nine years after the Royal Academy of Music commissioned a feasibility study to upgrade its central performance space, it has finally realised its ambitions with the completion of the 309-seat Susie Sainsbury Theatre designed by Ian Ritchie Architects. During the design process, a new 100-seat recital room above the theatre emerged as something of a bonus.
Resplendent in cherry joinery with red faux leather seating and a spectacular lighting array of 600 fibre-optic ‘crystals’, the theatre certainly looks the part, in sharp contrast to the carpet-walled, lecture-theatre-like space it replaced. But what of the acoustics? Sound quality is critical in any performance space but especially at a venue training elite young musicians and singers.
‘The academy attracts world-class students, and it is vital that they have outstanding spaces – visually and acoustically – in order to develop their talents for the world’s stages,’ says project architect Brian Heron.
From early in the project Ian Ritchie Architects collaborated closely with specialists at Arup to ensure that optimum acoustic provision was built into the design from the outset, and that the new theatre was equally able to stage opera, where the voices have no amplification, and musical theatre, which has significant amplification. ‘You have to make sure you get excellent results in both scenarios,’ says acoustician Philip Wright, associate director at Arup.
For opera, this meant working with the surfaces of the room to provide a series of sympathetic reflections that support the voice and hold it in balance, giving some sense of the room in order to provide an immersive experience. Musical theatre had different requirements, in particular the avoidance of too much reverberation. ‘While you don’t want a really dead space, you don’t want a space that’s too dominated by reflected sound. So there is a slight tension,’ he adds. Variable acoustic measures would normally be introduced to cope with the dual use. But the relatively small volume of space meant that the design team could avoid this by introducing sufficient texture in the room surfaces.
Built within what was originally a courtyard at the heart of the Academy’s listed Edwardian headquarters in Marylebone, the new theatre is a redevelopment of the 1970s Sir Jack Lyons Theatre, which was stripped back to its concrete slab. As well as improving sound quality and ambience, the Academy wanted to enlarge the orchestra pit by bringing it one metre further out into the auditorium to improve the connection between the two.
The design team accommodated this and made the space feel more intimate by bringing the sides in and introducing a new balcony level, increasing seat capacity by 40% on the same footprint. Aesthetically, the design was informed by the idea of the auditorium as a musical instrument, with the contours of the balcony and ceiling inspired by the curved form of stringed instruments. Wood was therefore the obvious choice to line the walls and ceiling, with cherry selected for its visual warmth. This volume then had to be tuned by the design team to provide the right acoustic.
‘In order to sound lovely for music, each surface has to temper the sound so that you have a smooth, even mix with no surface over-dominating,’ says Wright. For the proscenium, this meant relatively plain surfaces to help project the sound into the auditorium while the balcony, as a significant intervention in the space, needed to have a gentle curvature to throw the sound up and down. Particular attention was paid to the detailing – the balcony front is made up of many thin slats, each indented with a 1mm quirk to add texture and further aid the dilution.
As a large surface in a relatively small space, the ceiling had to be carefully detailed to avoid it over-dominating acoustically. Deeper structural elements were arranged to run front to back rather than side to side, since the latter would be too acoustically disruptive. Finer level surface details were used to avoid a large flat surface. The joiner built and acoustically tested 3m x 3m prototypes of the ceiling and articulated walls (see below).
Acoustic consideration was also given to the seating, with an array of 20 seats tested. A single pedestal, the Aida 125 from Figueras, worked best by allowing the sound to pass beneath more easily. Perforations were then introduced into the undersides of the seats so that when they are flipped up, unoccupied, sound can be better absorbed. Ventilation was another factor – it was essential that the introduction of air to the auditorium was inaudible. Rather than putting a plenum beneath the seats, the solution was to incorporate a system of aerodynamic, high velocity jet nozzles into the balcony. Air is extracted at fly tower level.
The second, smaller new space, the 230m2 Angela Burgess Recital Hall, is also a recording room. It has been cleverly accommodated above the main theatre with a mansard copper roof designed to be invisible from the street. However this 6m high space still has enough volume to achieve a generosity of sound that connects the phases together. The hall is a structurally independent box with its own slab that sits on top of elastomeric bearings to acoustically isolate it from the theatre below. The entire room, including the acoustically rated, steel main fire doors, is clad in lime-washed oak, with a central glazed oculus. Above, a series of wood-clad radial steel beams in the soffit
Susie Sainsbury Theatre auditorium lining
Great consideration went into the articulated surface of the cherry-lined auditorium wall which is broken up with vertical baton indentations to a depth of 50mm on the rear wall and 30mm on the side walls. The diffusion this achieves means it doesn’t reflect too much sound back into the audience. While this is important in both operatic and amplified musical theatre modes, it is particularly significant for the latter.
With a degree of randomness required, the composition is conceived as vertical books on irregularly spaced bookshelves. Many configurations were considered for the latter, which emphasise the horizontal lines of the auditorium. This included an initial arrangement of 200mm and 300mm high spacings between the shelves, which proved too acoustically busy. The final version consists of five shelves with spacings akin to both novels and encyclopedias.
This arrangement was made by James Johnson Joinery, who also accommodated the 20mm diameter, 25mm deep LED lighting into recesses within the articulated timber lining. The fittings were housed within the horizontal banding and the wiring behind the panels. These lights are conceived as ‘crystals’ dispersed from the exploded chandelier lighting feature, and also reference the historical use of candles to illuminate theatres.