Acoustic reflectors and the Concert Hall
Discover the role, history and renewal of the acoustic reflectors of the iconic Sydney Opera House Concert Hall.
Design for acoustic devices for Major Hall (now Concert Hall) (c. 1961) by Jørn Utzon, Mitchell Library, State Library of NSWSydney Opera House
Try this experiment at home
Record a conversation on your device and then play the recording back to yourself. Notice what's different? The sound in the recording sounds more fuller and different to the real thing.
Design for acoustic devices for Major Hall (now Concert Hall) (c. 1965)Sydney Opera House
Why does it sound so different?
The answer lies in the way our hearing focuses on sounds that our brains think are the most significant. It helps explain why music in a concert hall sounds better than at an outdoor festival (and why the sound can seem muffled if you're sitting right at the back).
It’s one of hundreds of laws of acoustics – a complex mix of geometry, architecture, physics and neuroscience – that must be mastered to make a hall sound beautiful!
Architects Leslie Martin, Jørn Utzon and Eero Saarinen discuss next steps (1957) by RIBASydney Opera House
Sydney Opera House acoustics
In 1957, Jørn Utzon was announced as the winner of the international design competition for the Opera House to be constructed on Bennelong Point. Soon after, the process of engaging an acoustician commenced, with Dr Vilhelm Lassen Jordan being appointed the following year.
Dr Vilhelm Lassen Jordan
Dr Jordan was a civil engineer and specialised in architectural acoustics. Considered one of the world's leaders of architectural acoustics he had acted as the acoustician in the design and construction of concert halls and theatres throughout most of the world.
Model testing
Dr Lassen directed that the acoustic design be guided by model simulation throughout the design and construction of the Opera House. A scale model was first built in 1959, with testing commencing shortly after.
Hall Todd & Littlemore
In February 1966, before work began on the interiors, Jørn Utzon was forced to leave the project. The interiors (Stage 3), became the responsibility of a consortium of architects - Hall, Todd and Littlemore. Peter Hall was appointed design architect to complete the project.
Dr Jordan continued to work as lead acoustician on the project with Peter Hall. During this final stage of the design and construction of the Opera House, Dr Jordan was joined by his son Niels and their assistant Peter Knowland.
Davis Hughes within a model of the Concert Hall (1968) by John O'Gready, FairfaxSydney Opera House
A change in brief
The original purpose of the ‘Major Hall’ (Concert Hall) was for opera, ballet and symphonic work however in 1967 it was announced by the NSW Government that the venue now operate as a single purpose concert hall. With a new brief the testing for the optimal acoustics continued.
In December 1971 the final toroidal form of the acoustic reflectors was determined. Having been termed ‘flying saucers’, ‘clouds’, and ‘doughnuts’, the objects had three suspension points and were constructed out of clear acrylic by Sydney based firm K. F. Plastics.
Manufacture and installation
The final design was manufactured by K.F. Plastics between March and September 1972, when 21 reflectors were installed in the Concert Hall in time for a ministerial site visit on September 5th.
Fine tuning
Further adjustments of the location and height of the doughnuts were being made until 17 December 1972, when the Concert Hall, was first tested at an orchestral performance given by the Sydney Symphony Orchestra for the builders of the Opera House.
The Sydney Opera House was officially opened by Queen Elizabeth II on the 20 October 1973. For nearly 50 years the Concert Hall 'doughnuts' were a backdrop to the array of inspiring moments and performance that have occurred in this grand venue.
Evolution of the Concert Hall
The Concert Hall was designed for acoustic music but within months of opening the venue was hosting amplified performances. Over the years various modifications were made to maximize the acoustic performance of the Concert Hall.
View of the canopy of acoustic reflectors (2016)Sydney Opera House
By 1989 the reflectors were needing to be replaced. New reflectors of a similar construction were installed and again replaced in 1994/5 and 2009. In 2009, infill disks were installed to further enhance the acoustic performance of the venue.
Acoustic testing in the Concert Hall (2009) by Jack Atley, Sydney Opera House TrustSydney Opera House
Preparation for Renewal
The infill of the doughnuts were an improvement however testing continued on how to optimise the acoustics of the Concert Hall. Additional shapes, sizes, materials were trialed under exposure to a variety of music styles.
Concert Hall Renewal
In 2020, the 21 former acoustic reflectors dating from 1994/1995 and 2009 were removed from the Concert Hall as the first step of the Concert Hall Renewal program.
Our heritage is a fundamental part of the Opera House identity, every aspect of renewal has involved widespread consultation and careful adherence to key conservation policies.
All works have been completed in line with the Opera House’s Conservation Management Plan, which safeguards the vision of Jørn Utzon and Peter Hall, and the Utzon Design Principles.
Still from 'The Concert' (2022) by Angela Goh, commisoned by the Sydney Opera House, as part of New Work Now, enabled by Tonkin Zulaika Greer ArchitectsSydney Opera House
The Concert
To celebrate the story of the reflectors, the Sydney Opera House commissioned artist Angela Goh to reimagine the former acoustic reflectors. The film 'The Concert' weaves together dance, song, costume, poetry and sound to reimagine these distinct objects.
Removal of the former acoustic reflectors (2020) by Daniel Boud, Sydney Opera House TrustSydney Opera House
Where are the doughnuts now?
Three were accessioned into the Opera House collection. Some were donated to the families connected with the design and manufacture of the objects and the remaining auctioned to fund heritage projects at the Opera House.
View of the updated Concert Hall (2022) by Chris Bennett, Sydney Opera House TrustSydney Opera House
Concert Hall Reopens
In 2022 the Concert Hall reopened following the biggest upgrade to the venue since opening in 1973. The improvements to the venue included enhanced access for people with mobility needs, new state of the art machinery, staging systems and enhanced acoustics.
View of the updated Concert Hall (2022) by Chris Bennett, Sydney Opera House TrustSydney Opera House
The Petals
Acoustic improvements included the replacement of the doughnuts with 18 specially designed reflectors in a petal shape. The acoustic petals have been finished in a semi-gloss magenta - the same colour as Peter Hall's signature magenta seen in the seat upholstery.
The sound in the newly-refurbished Opera House Concert Hall is immaculately clear, subtly astringent with fine layering, keen edge and polished textural detail.
Peter McCallum
The Sydney Symphony Orchestra performs on the opening night of the Concert Hall (2022) by Daniel Boud, Sydney Opera House TrustSydney Opera House
Celebration of sound
Renewal of the Concert Hall has been a resounding success, winning the National Architecture 2023 awards in the interiors and heritage categories. Improvements have been achieved without compromising the integrity of the majestic Concert Hall and the design regime of Peter Hall.
