SYDNEY OPERA HOUSESYDNEY OPERA HOUSE

Desirable acoustic properties of the Desirable acoustic properties of the auditorium can be contributed by its auditorium can be contributed by its architecture. The desired properties architecture. The desired properties

at left are correlated with the at left are correlated with the measurable parameters at right.measurable parameters at right.

Projection of SoundA good auditorium will accomplish effective

projection of the sound to the rear of the auditorium so that those distant listeners will not

experience the extreme loss of sound level caused by the inverse square law. That projection is normally achieved by having a sufficiently long

reverberation time. Another significant contributer will be a high, reflective ceiling to reflect sound to the back of the auditorium.

Even DispersionSound is more pleasing if it is evenly dispersed, with no

prominent echoes, no significant "dead spots" or "live spots" in the auditorium. This even dispersion is usually achieved by avoiding any focusing surfaces and avoiding large flat areas

which reflect sound into the listing area. Sometimes it is desirable to add some anti-focusing surfaces.

• After all the main characteristics of auditorium acoustics are accounted for: proper reverberation

time, longer reverberation time for low frequencies, even dispersion, etc., there still remain nuances which cause persons to prefer some apparently

comparable auditoriums over others.