30 Oct Theatre Acoustics: Ancient Intuition Meets Modern Scientific Rigour
Many ancient amphitheaters are recognized for their wonderful acoustics. Legend says that in the Colosseum, the emperor could hear the whispers of people sitting in the upper seats. In fact, ancient architects had almost no knowledge of architectural acoustics; instead, they achieved results through experimentation and intuition. Yet in this, they identified key acoustical principles that continue to play a role in architectural acoustics today.
Consider the theatre at Epidaurus, the ancient Greek theatre built at the end of the 4th century BC. It seats 14,000 people, yet even in the nosebleeds, everything that happens on stage is perfectly audible. That’s because the theatre is made of limestone, a material that reflects sound, and the theatre is laid out to channel the actors’ voices from the stage to the audience—all the way to the top row.
These days, instead of limestone, we acoustical designers use wall and ceiling panels to control sound reflections. Where ancient designers used terrain features like hillsides or depressions to direct sound, we position walls, ceilings, and floors to shape the room. And the world is certainly much louder now than it was during ancient times, so today’s acoustic practitioners understand the effects of environmental and HVAC noise on audiences and performers, and can recommend solutions to insulate a space from such noises.
A room’s shape and the reflective quality of its finishings affects reverberation times. Since lower reverberation times improve speech intelligibility, acoustically dry spaces are well suited to drama. Music, on the other hand, sounds better in a more reverberant space, with longer reverberation times and carefully positioned reflecting surfaces that allow the audience to hear a blend of the instruments and the musicians to hear themselves.
Contemporary Theatre Design: A Spotlight on Versatility
Today’s theatres are often used for both drama and music, so acoustic designers need to find solutions that serve these contrasting acoustical needs.
When providing acoustical design services for Buhler Hall in Gretna, Manitoba, BKL’s acoustics team used variable design elements to tune the room’s reverberation. The space features both musical and dramatic performances, so vertically pivoted periaktoi were installed. Each periaktoi is 5 metres high with an absorptive side and a reflective side, and theatre users can position them as needed.
Buhler Hall is noted for its musical and choral acoustics. When the hall opened, Henry Engbrecht, a former choral professor at the University of Manitoba, said that it “rivals the best small halls in Western Canada. An expansive stage projects sound with great clarity and rewards the performer richly by creating an intimate audience-performer experience.”
A Scientific Approach to Architectural Acoustics
In 1895, American engineer Wallace Sabine was asked to improve the acoustics of the Harvard University lecture hall. The hall was notorious for its terrible echo and hum, and the students could hardly make out the words of the lecturer. At the time, few believed in the idea of the proactive engineer, and the bad sound in the hall was taken for granted.
For several months, Sabine conducted acoustical experiments—trying different carpets and varying the number of people in the hall. Through these experiments, he made formulas and identified dependencies. As a result, he was able to reduce the echo effect by using specially selected sound-absorbing materials. Following his success at Harvard, he was offered a job as an acoustical consultant during the construction of the Boston Symphony Hall, which is today considered one of the best acoustic spaces in the world.
Understanding Reflections: A Formula for Success
Sabine and the ancients knew that acoustics are influenced by a space’s shape, size, layout, and finishings. While the ancients relied on intuition, and trial and error, Sabine quantified these influences through his scientific approach, and developed a formula that theatre designers still use today.
Using appropriate expertise, experience, and calculation tools, today’s designers can accurately calculate a room’s acoustical environment before it’s built. So acoustical issues and fundamental defects can be identified and addressed before construction even in any space, regardless of its complexity.
At BKL we understand that today’s performance spaces often host a variety of events—from drama and lectures to choirs and concerts, both amplified and unamplified. Along with our expertise and experience consulting on room acoustics, we have the latest software and instruments to deliver accurate assessments and predictions. We can provide efficient and effective design advice for your next project, whether it’s a new building or refit. If you want to learn more about architectural and theatre acoustics, contact us today.