John O'Keefe — Toronto AES -- February 28, 2012
Jeff Bamford introduced John O'Keefe and briefly provided his background and credentials. Mr. O'Keefe received his Bachelor of Applied Science from the University of Toronto in 1981 then a Masters in Sound and Vibration Studies from Southampton University in 1985. His work includes the Princess of Wales Theatre, the Young Centre and, in association with Soundspace Design, The Four Seasons Centre for the Performing Arts. John is a principal with Aercoustics Engineering Limited and has presented papers and lectures throughout the world. He is the winner of several awards including The Schreyer Award.
John thanked everyone for coming. As an introduction to highlight what was done in Vancouver, he discussed the history of acoustics referring to it as a 'multi-dimensional' experience". He discussed some of the terms encompassing this experience including reverberation, early decay, clarity, precedence effect, the Haas effect, and spatial impression.
He went on to talk about the use of early reflections and lateral energy in the design of buildings. Our perception of sounds from the sides is beneficial, enhancing the listening experience. Other points of interest are acoustic intimacy, warmth, and loudness.
He discussed the actual design next. A lot of things needed fixing. The only thing the Queen Elizabeth building had was clarity. Control of ventilation noise contributed to compliments from the Vancouver Opera Company on the 'warmth' the space gained due to the de-masking of bass frequencies.
Two priorities (at odds with each other), influenced the acoustic design of the renovation of Vancouver's Queen Elizabeth Theatre: the room had to work for the unamplified Vancouver Opera, as well as amplified musicals, and "soft seat" rock-and-roll shows.
Vancouver's theatre was judged 'dry'. The acoustical challenges were dictated not by the architect but by the owner's very real concerns about satisfying the acoustical needs of the opera and the need to pay the bills with a high seat count of about 2,750 which were intended to stay. That meant a very wide room. Responding to this, the acoustical design borrowed ideas from Christchurch Town Hall and Berliner Philharmonie.
When a third of the construction budget disappeared, a complete acoustical re-design was initiated. Emphasis was now on the Christchurch model. The idea was to remove the ceiling. Height to width ratio does have an effect to the decay time. Reflectors in the ceiling and strategically located balcony facia reflectors were used. The curved reflectors were giving the 'ski slope' seats good lateral energy.
Using software intended for lighting in green buildings, the orientation of reflectors on the balcony facia was designed to within a single degree of tolerance. The result is a very wide post-war proscenium arch venue that completely covers the audience area with early lateral energy. All parties (and genres) agree to the success of the renovation.
The talk closed with a question and answer period.
