An Interview with Erik Bergal about the Jinji Lake Concert Hall, Maestro Toyota's assistant, Nagata Acoustics
SZSO: The wood for the stage is Alaskan Yellow Cedar. Why this wood?
EB: The stage surface is of key acoustical importance since it is the closest sound reflecting surface. Alaskan Yellow Cedar has a fine grain that is strong enough to physically support the musicians while flexible enough to vibrate with the orchestra. Instruments like cello and double bass make a physical connection with the stage via their endpins and rely on the sympathetic vibrations to project their sound.
SZSO: What is the purpose of the fans on all the walls?
EB: The fans on the walls are used for acoustic diffusion. Incoming sound is scattered in many random directions. This creates an even sound field in the hall. You can think of this in the way a mirror creates a sharp reflection while frosted glass results in soft reflections.
SZSO: What is the purpose of the steel mesh on the balconies and ceiling?
eB: The steel mesh is acoustically transparent. This means that it can be used to create visible architectural features without affecting the acoustical condition.
SZSO: What is reverberation time and how is it important?
EB: Reverberation time is a measure of how long it takes for sound energy to dissipate in a space. The metric is related to the impressions of richness and warmth. The Jinji Lake Concert Hall benefits from a tall ceiling and spacious volume for the number of seats, resulting in plenty of space for sound to reverberate. It is important to remember that there are many other factors which influence the acoustic quality of a hall and that it is impossible to summarize the acoustical quality with a single value.
SZSO: Why are there seats behind the stage?
EB: Adding seats behind the stage has many advantages. First, the seats can be used by the chorus so they are not crowded on stage. When choir is not needed, the seats can be used by the audience. Second, moving seats behind the stage moves the orchestra closer to the center of the hall reducing the average distance to any audience seat. Third, facing other audience members increases the sense of visual intimacy. These seats provide a unique place for the audience to sit where they can see the animated face of the conductor.