Perfecting sound in the performing arts

By Payam Ashtiani, P.Eng.

Newmont Stage at BMO Theatre Centre started hosting live, on-site theatrical productions in July 2021. Photo by Andrew Latreille

It is hard to recall the last time a live audience watched a play, musical, or concert in a theatre. The arts industry was devastated when the COVID-19 pandemic forced a swift curtain call for theatres, silencing performances around the world.

The return to theatres is difficult to predict. Performing arts of all kinds—music, theatre, dance, and opera—are in the mass-gathering business, bringing people together in close quarters to share an experience. In an age of social distancing, the return to live in-person entertainment remains uncertain.

That said, there have been beautiful expressions of the arts in various forms shared from a distance—from porch performances to Zoom concerts, artists have found creative ways to connect and stay relevant.

As good as these events are, there is a strong desire to return to the way it was, not just for those whose livelihoods depend on it, but for the public whose mental health is greatly boosted by the arts. The arts have a history of resilience, bouncing back from the plague and World War II, so the question is not will these events return to theatres and performing arts venues, but more so when will they return?

When live events do return, the pandemic will have permanently impacted everyone’s behaviour, so adjustments will need to be made to ensure patrons feel comfortable gathering again. There will be many who will not feel comfortable returning to a physical venue and may wish to enjoy virtual experiences only. This is the time to use imagination and creativity to stage performances remotely that replicate the in-person experience and find solutions that will help improve the live theatre experience when an audience can participate.

Plexiglass barriers and staying 2 m (6 ft) apart does not work in performing arts because some social distancing solutions can have a significant impact on acoustics. The following are some key considerations when redesigning performing arts venues to accommodate safety guidelines without compromising on acoustics:

Keep the seats and space out patrons  

Located in Vancouver, the 2800-seat Queen Elizabeth Theatre hosts Vancouver Opera and Ballet British Columbia. Photo by Ed White Photographics.

Many have become accustomed to keeping a distance of at least 2 m. Theatre seating typically provides 0.8 to 0.9 m2 (9 to 10 sf) per patron—much less than required for safe distancing. The temptation may be to remove seats to ensure proper spacing; however, removing the seats comes with significant consequences to the acoustics and can be detrimental to the audience experience. From an acoustics perspective, those empty seats provide acoustic absorption and play a vital role in soaking up some of the sound and stopping it from becoming too reverberant. Rather than removing seats, sections can be blocked off to keep patrons further apart. Retaining seats also provides the venue with more flexibility. For example, if a larger family living in one household or bubble would like to attend, they can purchase their seats together. Another option could be gallery or box seating to help spread out the audience safely.

Do not replace soft surfaces with hard

Wiping down and sanitizing surfaces has become second nature. So, when designing a space with group seating, it may seem like the safest option would be to design a space with non-porous materials for cleaning purposes. Typically, this would be a good option but in a theatre setting, the plush materials are more than just comfort, they absorb sound. The acoustics will change dramatically with hard seating based on the occupancy rates since people in hard seats will provide a similar level of acoustic absorption to plush seating. If the venue opts for wipeable or non-porous materials in the design, creative solutions may be required to return acoustic absorption to the space.

Take a close look at the air flow and exchange

One option to help prevent the indoor spread of the virus is to increase the amount of fresh air coming into the building from windows and doors. This is not an option in a theatre setting where external noise sources would be a major distraction. The alternative is to consider the air flow and exchange within the building. However, HVAC systems need to allow for much higher ventilation rates, which could lead to noisier air flow. To mitigate this, there must be slower air movement which is not only quieter but also provides good return for energy management and patron comfort.

There are other considerations around air flow that do not necessarily impact acoustics but the safety and comfort of patrons around the spread of airborne aerosols. Typically, the design either supplies air from the top so it falls on the audience or sends air upwards from the bottom with a displacement system. In post-pandemic design, the preference is to have air supplied from the bottom to ensure any airborne aerosols are carried up and away from other audience members rather than blowing down onto the crowd. This would need to be analyzed in greater detail using computational fluid dynamic (CFD) modelling that demonstrates the movement of air in far greater detail than traditional mechanical design.

Do not overdo spacing on stage

A pre-pandemic shot of the Royal Conservatory Koerner Hall opening night. Photo by Tom Arban Photography

Social distancing is now the usual but for musicians, this is not natural. Being spaced further apart can be detrimental to their performance because it affects how well they can hear each other which ultimately impacts their ability to play in unison. The farther apart they are, the longer it takes sound to travel back and forth which can cause a delay. This puts extra pressure on stage acoustics to help support the musicians. If the musicians must stay at a significant distance, in-ear monitors may be beneficial. They will also have to rely more on conductor visual cues than their ears.

To cover or not to cover?

Wearing a face mask muffles speech, making it difficult for others to understand. So, imagine the impact this would have on singing or instruments. Over the past year, many different workarounds have been used to allow online parades or band performances—from fabric coverings over wind instruments to limit aerosol spread to plexiglass dividers. The challenge is finding a way to effectively reduce the spread of aerosols without deadening sound. While plexiglass dividers are being effectively used in the retail space, they have many downsides for the performing arts. It will decrease the ability for musicians to hear each other and play in ensemble. It could also make sound even louder for musicians, many of whom already experience hearing loss.

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