ACOUSTICS
A ustralia’s Sydney Opera House is
one of the busiest cultural hubs in
the world with probably the bestknown
external appearance –
spectacular architecture designed
by the Danish architect Jørn Utzon. More than
10 million visit the site annually, including more
than 2.1 million performance and tour patrons.
However, the original design and construction
of the building has left it with some challenges.
“Beginning a project with an unrealistically low
budget, starting construction before detailing
important parts of the design and changing the
fundamental requirements in the middle of a
project will sound familiar to most readers,”
comments Gunter Engel, project manager at
Müller-BBM. “The good news is that all these
issues do not necessarily stop a project from
being a tremendous success. The bad news is
that sometimes it takes decades until early
mistakes are remedied.”
Cave-like pit
The Joan Sutherland Theatre is the opera venue
at the Sydney Opera House, and the venue most
impacted by changes made during the
construction. As a result, the Sydney Opera
House got a beautiful audience space with about
1,500 seats, but 70% of the orchestra pit is
covered by the stage.
“For the audience, and even more for the
orchestra, this impacted the acoustics,” says
Engel. “The projection of sound from the pit
to the audience was uneven, especially for
instruments located deep in the covered part of
the pit, and orchestra members had to play in an
unusual formation with the woodwind section
cramped in the right side of the open part of the
pit and the strings in the left part.”
After 40 years of nearly uninterrupted
operation, the theater’s stage machinery had
to be replaced for safety and reliability upgrades.
The closure of the theater from May to December
2017 offered a unique opportunity to improve
the acoustics and so in 2015, Müller-BBM was
appointed to deliver this.
Research mission
To gain an in-depth understanding of the
situation, extensive acoustical measurements
were performed together with multichannel
recordings by means of dummy heads distributed
all over the auditorium and in the orchestra pit.
These recordings, in combination with attending
numerous rehearsals and performances, provided
valuable information about the existing situation.
The usual approach – extending the orchestra
pit toward the audience – was not viable in the
Joan Sutherland Theatre. Tie beams holding the
Main and top: The key
challenge was that 70% of
the pit is under the stage
Right: The pit now has
a fixed diffuse, partly
absorbent cladding and
mobile absorber elements
AUDITORIA 2019 VOLUME ONE 45