Acoustics of a selection of famous 18th century opera houses: Versailles, Markgrafliches, Drottningholm, Schweitzingen.

Abstract

This paper presents the analysis of the acoustical measurements conducted in 8 renowned baroque Opera Houses located in France and Germany. Still in authentic condition to their time of usage, and incorporating the historical changing scenery system (shutter and groove), these Houses have undergone little renovations. The acoustical analysis investigates the performances of these great Houses using energy parameters, balance between stage and orchestra parameters, 3D intensity plots, new spatial distribution parameters and timbre frequency analysis. The objective of the study is to deduce (for the Constellation Project) design targets for a medium size Opera House against these benchmarks and also to revisit the use of the lateral changing scenery system as used in the Baroque era, as an original scenery design concept for a new House. The paper presents the unique qualities of the rooms, illustrates some of acoustical benefits of the 18th century Opera House design characteristics, discusses some differences in the design approach between the Italian and the French traditions and proposes new perspectives for modern Opera Houses design.

Full text

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Acoustics of a selection of famous 18th century opera
houses: Versailles, Markgr¨ afliches, Drottningholm,
Schweitzingen
A. A A Bassuet
Arup Acoustics, 155 avenue of the americas, New York, NY 10013, USA
alban.bassuet@arup.com
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This paper presents the analysis of the acoustical measurements conducted in 8 renowned baroque Opera Houses
located in France and Germany. Still in authentic condition to their time of usage, and incorporating the
historical changing scenery system (shutter and groove), these Houses have undergone little renovations. The
acoustical analysis investigates the performances of these great Houses using energy parameters, balance
between stage and orchestra parameters, 3D intensity plots, new spatial distribution parameters and timbre
frequency analysis. The objective of the study is to deduce (for the Constellation Project) design targets for a
medium size Opera House against these benchmarks and also to revisit the use of the lateral changing scenery
system as used in the Baroque era, as an original scenery design concept for a new House. The paper presents the
unique qualities of the rooms, illustrates some of acoustical benefits of the 18th century Opera House design
characteristics, discusses some differences in the design approach between the Italian and the French traditions
and proposes new perspectives for modern Opera Houses design.
1Introduction
Opera house design evolved rapidly in the 17th century
across most countries in Europe. By the 18th century,
characteristic design practices had emerged. This study
investigates the design traditions of the 18th century by
using new scientific tools to test the acoustics of some of
the most renowned opera houses of this era.
The tested houses include L’Opéra Royal in the Chateau de
Versailles, France; Markgräfliches Opernhaus in Bayreuth,
Germany; Drottningholms Slottsteater near Stockholm,
Sweden; and Rokokotheater in Schwetzingen, Germany.
Still very much in use today, these houses were selected for
their authentic conditions representative of their time and
for their renowned acoustics over their long history. These
famous opera houses, as well as several others, have been
identified as benchmarks for the ConstellationCenter
project, a new performing arts center to be located in
Cambridge, MA.
The initial research visits took place in 2004. The acoustic
measurements included music recordings, including a
soprano singing with anechoic music accompaniment,
along with B-format and
(Soundfield ST-250 and Neumann KU-100). The test
signals were sine sweep played through a dodecahedron
and a subwoofer and recorded digitally (Zaxcom Deva II).
binaural measurements
2Historical Data About the Houses
All of these houses integrate the 18th century “shutter and
groove” scenery system that consists of regularly spaced
slots on a raked-floor stage and painted scenery on flats that
move together in a synchronized manner. This scenery was
used to create spectacular scenic effects, including the
visual illusion of perspective scenes to a vanishing point or
points in the rear of the stage. Other scenic elements
included flying machines (such as for flying angels) and
sound making instruments (for thunder, rain, wind, etc).
Such theatres were built into palaces and civic structures
throughout Europe. Several family traditions had
established a famous reputation such as the Galli da Bibiena
family of Bologna.
It is Guiseppe Galli da Bibiena and his son Carlo who
designed the interior of Markgräfliches Opernhaus in
Bayreuth, Germany for Margravine Wilhelmine of Prussia
(an artist herself), sister of Frederick the Great, who had
decided to create a miniature Versailles in Bayreuth. The
Markgräfliches Opernhaus opened in 1748; it seats 800
people and includes many classic 18th century opera house
characteristics. The auditorium is curved and elongated.
The balconies with boxes and galleries are lined-up
vertically, reducing the sound absorption of the audience.
The balconies do not connect with the proscenium.
Decoration is in the Baroque style.
It was Lully’s Persée that inaugurated L’Opéra Royal of the
Chateau de Versailles on 16 May 1770 for the celebration
of the marriage of the Dauphin, the future Louis XVI, with
Marie-Antoinette. Built by Ange-Jacques Gabriel, the
theatre had a seating capacity of 1000 (it now seats 712)
and it incorporated some of the best scenery equipment.
The architect had chosen an elliptical form for the
auditorium, with the King’s box at the visual and acoustical
focal point, with a parterre, avoiding deep balcony recesses
and a continuation of seats along the sidewalls to the stage.
The room is decorated in a neo-classical style with painted
wood to imitate the effect of stone.
Drottningholms Slottsteater was opened in 1766. It was
constructed by the architect Carl Fredrik Adelcrantz at the
request of the Swedish Queen, Lovisa Ulrika. Part of the
palace complex that is still the private residence of the
Swedish royal family, it has been classified as a UNESCO
world heritage site. The architect had chosen an original
elongated rectangular shape for the auditorium, a form that
he also used for Confidencen Theater, also near Stockholm.
This shape results in an auditorium acoustics that benefits
from some of the qualities of rectangular rooms like the
great music rooms of the same era. Its interior is decorated
with French patterns painted on stucco and papier-mâché.
Drottningholm is also very famous for its complete stage
scenery system still very much in use.
Today, the Rokokotheater in Schwetzingen is rarely
mentioned in books on acoustics, and this opera house is
one of the surprising discoveries of this study. The house
opened in 1752 for Karl Theodor Prince-Elector, Count
Palatine and Duke of Bavaria, and was used for drama and
opera. It has a capacity of 450 seats. It was conceived by
Nicolas de Pigage, French sculptor and architect. One of the
most interesting characteristics of this opera house is the
second balcony recess above the first one which, combined
with the sculpted under-balcony surface between the
arches, creates the most powerful acoustical effect at most
seats as explained later in the acoustical analysis.
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Figure 1: Drawings of Markgräfliches Opera House top,
L’Opéra of the Palace of Versailles middle, Drottingholm
Palace Theater bottom
Figure 2: Drawings of Schwetzingen Schlosstheater
3Acoustic Analysis
3.1 Stage Support
One of the most renowned qualities of these houses is how
they support singing and the ease at which singer can
project his or her voice. Some of their characteristics are
explained below.
The scenery equipment in these houses is mostly composed
of painted canvas, ropes and wood framing. The sides of
the stage house the scenery system and the ceiling of the
stage is at the same height as the ceiling of the auditorium.
These houses do not have the modern fly tower. In addition,
the scenery principle which uses the lines of the proscenium
arch depth as the starting point of the perspective illusion
result in a deep proscenium arch, typically around 3m.
These elements combined result in a live acoustics inside
the stage house due to the low amount of sound absorption
created by the scenery (RT in these stage houses is 20%
longer than in their auditorium), to a low and solid sound
reflective surface above the head of the singers (loudness
measurements inside these stage houses range from +4dB
to +10dB from downstage to upstage), and to near and wide
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sound reflective proscenium surfaces around and above the
singers.
The effect of reverberation on stage can be shown with the
calculations of RT30 at 3m from the source (singer
accompaniment position). At this distance, the early decay
of the reverberation is already within 85 to 100% of the
reverberation indicating the liveness quality on stage.
Values of support parameters ST1 early were calculated
from measurements conducted in the middle of the
proscenium arch. Compared to measurements conducted in
recently completed opera houses [2, 3], these values exceed
by 3 to 10dB numbers typically measured in modern opera
houses and are indicative to the important sound reflectivity
of the proscenium arch and stage. Versailles and Bayreuth
have the longest reverberation (“longest resonance”) but
lower early support due to their size; Drottningholm and
Schwetzingen show the highest early support values
(highest “engagement”) but have shorter reverberation time,
especially in Schwetzingen. In Drottningholm, the EDT
equals RT30 at 3m, which suggests that the sense of
liveness on stage would be the strongest.
3.2Energy Balance in the Auditorium
The average loudness parameter for a source on stage
ranges from +1dB to +5dB while the loudness difference
between the stage and the orchestra ranges from -1.5dB to
-2.5 dB. These houses were smaller and louder and
therefore require less vocal energy from singers. This might
also have allowed a wider variety of singing techniques as
voice would not have to be forced.
The orchestra is located on the floor in front of the stage
instead of a deep pit. Compared to measured data in modern
opera houses [2, 3], the orchestra loudness is higher than
the stage loudness while it is the opposite in modern venues
(typically louder by 0 to +2dB on average). This indicates
that the loudness of these houses would have helped to
compensate for the musical instruments of the 18th century,
which were quieter than modern. The highest values of
loudness are calculated in Drottingholm which exceeds
Schwetzingen with a similar volume. This is the
consequence of the shoebox shape of the auditorium
creating strong sound reflections between the large and
exposed parallel surfaces.
The vocal clarity indicated by D50 parameter fluctuates on
average around 50% (omni-directional source). Minima are
experienced in Drottingholm showing the influence of the
shoebox shape creating late sound build-up resulting in
lower vocal clarity, (predictions indicate that D50 would
rise up to 45% under occupied conditions). Maximma are
achieved in Schwetzingen due to its short reverberation
time and its sound reflective surfaces (see section 3.3).
Orchestral clarity varies from +1dB to +4dB. This is higher
than in modern opera houses (typically between -4dB to
0dB) because the modern pit usually shields some of the
direct sound and reduces the orchestra clarity. Higher
musical clarity in these houses would have supported music
performances integrating substantial amount of musician
ornamentations and which would have been more suited for
17th century musical compositions that were more melodic
than chromatic.
The “running reverberance” parameter represented by EDT
shows very small variations in Bayreuth. This demonstrates
a uniform distribution of energy across the auditorium and a
density of sound reflections. This could show the combined
effects of the circulation of sound due to both the
reflections on the balcony fronts and the architecture
ornamentation creating sound diffusion as shown by the
values of 1-IACC late which are highest in Bayreuth. The
EDT parameter is the highest in Versailles, and the lowest
in Schwetzingen. The ratio of EDT versus RT is the highest
in Drottningholm, indicative of liveness and also
confirming the influence of the rectangular shape of the
auditorium.
Figure 3: Source on stage or in the orchestra. Grey lines
indicate predicted occupied condition. Versailles (V),
Bayreuth (B), Drottingholm (D), Schwetzingen (S)
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3.3 Reflection Sequence
One of the most interesting characteristics of these houses
comes from the development of their form and shape,
which creates the most beautiful acoustical effect. A 3-
dimensional impulse response is plotted at one of the most
representative position in each hall, using a graphic
technique as explained in [4]. The source is located on the
stage in the middle of the proscenium, with the exception of
Bayreuth, where the source is located in the orchestra.
Versailles is shaped as an ellipse to focus the sound at the
rear on-axis. The plot of the 3-D impulse response at this
position clearly shows the effect of the focused reflections
occurring from the side walls. These reflections arrive
within the first 15ms of the room response, which would
create a significant increase of the sensation of intimacy
(acoustical illusion of proximity), loudness, vocal clarity
and early envelopment (source size). At this position, the
room response is then characterized by the ceiling
reflection (occurring within the 15 to 40ms time frame) and
by the upper corner sound reflections (40 to 100ms) which
would contribute to the sense of late envelopment.
A 3-D impulse response is plotted in Drottningholm for a
position located 4 rows behind the King’s position (the
King and Queen’s boxes are at the front of the house). Side
wall and ceiling reflections are occurring within 15 to 40ms
closely spaced in arrival time. The impulse response then
shows strong reflections within 40 to 100ms, evenly
distributed in the lateral space, which demonstrates the
effect of the parallel wall surfaces of the auditorium. The
experience at this seat would be loud, live as explained
above (EDT) and very enveloping, both in terms of source
size impression and late envelopment due to the bouncing
of late reflections between the side walls.
It is in Schwetzingen that one of the most remarkable sound
reflection sequences can be experienced. Firstly, the
auditorium incorporates large sound reflective surfaces
around and in front of the proscenium and on the side walls.
Secondly, the room has a curved sound reflective surface
underneath each balcony following the “U” shape form of
the auditorium and is cut into arches between the columns.
This, combined with the second balcony recess, creates a
quick reflection of sound at every seat on the balcony and
on the orchestra level. The 3-D impulse response measured
in the real room is plotted for a seat on the orchestra level at
the rear. It shows the reflection coming from the side walls
and the rear because of the “U” shape of the hall, along
with the upper portion of the hall including the second
balcony underside and the ceiling. This creates a
composition of reflections balancing the front/rear and
low/high lateral sound within 40ms as rarely achieved in
other venues, and at most seats in the auditorium, as shown
by the 1-IACC early parameter illustrated on Figure 4.
3.4 Materials
Some of the renowned qualities of these houses concern
their “resonance”, which is often attributed to their finishes.
The inside of these houses are mostly made of soft
materials such as thin wood, papier-mâché or stucco. These
materials were shaped and painted to create the illusion of
real decorations and a deep field of perspective. By
observing the plots of reverberation decay in narrow
frequency bands in these houses at a representative position
in the hall, a drop-off below 200Hz can be noticed in
Versailles and Drottningholm, with a gap between 63 and
125Hz at Schwetzingen and Bayreuth, which is relatively
flat above that frequency range. These results could reveal
the effect of the sound absorption of the soft finishes as it
could be predicted, and that these soft finishes would
control the low frequency build-up that would have
occurred otherwise with harder materials. In each of these
houses, a low frequency rise below 63Hz is also apparent.
An assumption could be made that the soft finishes become
acoustically transparent to sound at such frequencies which
would then be reflected back in the auditorium by the heavy
and thick stone masonry walls supporting the hall. It is also
notable that the transmission of vibrations through the soft
finishes was used for certain theatrical effects such as the
use of a faceted stone ball that was rolled on the stage to
make the entire house resonate creating a “thunder effect”.
Figure 4: Top left: Versailles, top right: Bayreuth, bottom
left Drottningholm, bottom right Schwetzingen
5 Conclusion
Towards the end of the 19th century, the opera house
became larger, and its form more circular bringing the
audience closer to the stage and improving sightlines. The
proscenium was enlarged, the perspective scenery effect
was abandoned and the deep orchestra pit starts to be used.
These are the elements that define our modern opera house
archetype. The houses analyzed in this study were created
at the pinnacle of the perspective scenery era. They are
smaller and easier to sing in, tend to be more elongated
with a smaller proscenium for the perspective scenery
effect, do not use an orchestra pit, and therefore had
different acoustic characteristics than the later houses. This
study demonstrates the richness of their acoustics, including
the diffused reverberation of Bayreuth created by the lined-
up balcony fronts and ornamentation derived from the
Italian tradition, the musical acoustics of Drottningholm
with its shoebox shape derived from music rooms, the
sound focusing combined with reverberation using an
elliptical shape at Versailles, and the remarkable reflection
sequence of Schwetzingen indicative of the early departure
toward a more democratic design and maybe a French
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