Why is it that some opera houses support and enhance the singers and others muffle them? Why do pit orchestras overwhelm singers in some houses, while too weak in others? In many halls, dead spots occur in some seats where the brass and percussion are all too prominent and the strings are strangely absent. The balcony may sound alive and clear, but in the orchestra seats, the sound is so distant and flat.

Most opera companies struggle with facilities that were built decades ago to serve a broad range of not-for-profit performing arts and for-profit users. For those who perform or operate an opera house that is less than ideal acoustically, there are successful, real-world approaches for renovation.

I have advised on acoustic renovations of historic movie houses into fine homes for opera companies, from the Cleveland Opera at Playhouse Square’s State Theatre, to the Detroit Opera at the Michigan Theatre. Since they were built to serve as the home for film, movie houses’ sightlines, pit, stage, and lobby often do not meet the expectations of modern opera companies or audiences. A large single balcony hall is best suited for viewing and hearing action in the center of a movie screen, not a pit orchestra and live singers, yet with acoustic upgrades, the movie palace has proved to be a successful, and even outstanding, opera house.

Typical vaudeville pits from the early 1900s were built to accommodate 15 to 20 musicians in a small and narrow dropped zone in front of the stage. The modest pit served silent films and live musical numbers. A modern opera house pit must accommodate up to 100 musicians with comfort, ADA access, and excellent acoustics. The pit design, to be ultimately successful, needs to be mindful of the musicians’ needs first.

There is a desire by many owners to reduce the depth of the pit—upstage to downstage—because of the understandable need for highly priced, front-row seats to be as close to the stage as possible. While it is advisable to limit the depth, we can make the pit wider, left to right—as wide as possible.

The new Koch Theatre pit at Lincoln Center is 24' deep at the center—no need to go deeper than that. The guideline used for years is 16 to 20sq-ft. per musician, depending on the makeup of the instrumentalists; piccolo players, for example, need less space than timpanists. Limit the number of musicians that must play under the overhang of the stage, because they find it too loud there and very difficult to hear other musicians. Eight to 10' under the stage is often enough to allow some room for musicians to circulate and some room for the sound to expand and bloom.

Other tips for the pit (and this applies to many pit designs, not just movie palaces):
A wood pit floor with large air space below makes a resonant surface for the bass and cellos. Even a plywood subfloor is better than concrete.

In order to improve pit balances, heavy velour drapes on tracks on the upstage wall of the pit behind the high energy instruments (brass and percussion), and not near the weaker instruments, is inexpensive and beneficial.

By adjusting and repositioning the musicians in the pit, vast differences in pit balances and levels can be made. For example, moving from a traditional pit setup—winds on one side, brass on the other—to a more orchestral set where the winds are centered and horns off to the side can improve balances to support, rather than work against, the movie house acoustics.

In the typical historic movie house, a deep balcony overhang and a concave ceiling directly over the pit causes real balance issues in the seating. In the Carpenter Center renovation in Richmond Virginia, the concave ceiling focused some instruments in the center orchestra seats, creating “hot spots,” while missing others entirely. The answer was to hang custom acoustic clouds made of scenic materials to look like actual clouds suspended on winched cables over the pit. These foiled sound focusing and hot spots off the existing atmospheric ceiling.

I have had the unique experience to have worked on renovations of three of the major opera houses built in the 1960s, the Seattle Opera House, the Kennedy Center Opera House, and The New York State Theatre (now the Koch Theatre) at Lincoln Center. All three were built after the age of the movie palace and modeled on other successful rooms in Europe and America. We saw (and heard) room for improvement in all three halls.

HVAC systems in the 1960s were unsophisticated and contained such now taboo materials as asbestos insulation and cork vibration pads. It was considered sufficient to blow cold air from the ceiling 40' to 50' up, hoping it would cool the patrons far below, using an HVAC system similar to office parks and shopping malls. However, noise from HVAC ruins otherwise acoustically sound halls by covering up the positive sound reflections from walls and ceilings that give a space its characteristic aural live-ness or presence.

We designed the three pits to be more commodious and sonically supportive, and more thermally comfortable. In fact, we turned the wood pit floor in Seattle and New York into ventilation systems by hand-drilling thousands of small holes and moving ventilation air through the holes. The wood floor surface lost none of its resonance, and air moves slowly and silently, making the pit more thermally pleasant.

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Pointers for a quieter air system:
Air that moves quickly is, by definition, noisy. This can be easily diagnosed. Have the building operators stop or slow down the speed of the fans serving the seating area. Then have the musicians play in the pit with the air off and then at full speed. If you hear a real difference in sound quality, brightness, and resonance, you have this most common of acoustic problems.

Make sure the air system is balanced for lowest noise possible. While “how” a certified air balancer does this is a bit complicated, air flow can be reduced in an excessively noisy grille that sets the levels for the entire room, while sending air to other grilles that are not noisy. We have used opened grilles that were previously 90% closed, and noise problems and acoustics improved.

In two of these halls, we actually reversed air flow, so the air was delivered, rather than exhausted, at the floor in small grilles under the audience. This is quieter and an energy saver.

When it comes to wall- and ceiling-shaping for opera houses, a complex topic, I can make a few general statements. For the 3,000+ seat Seattle Opera House (Marion McCall Hall), renovated in 2005, the shaping of a natural acoustic hall was critical, much more so than for a 1,200-seat space. With the same number of singers and instruments, the larger hall is expected to amaze and transport the larger audience that much more. Every person absorbs sound, so the walls and ceilings must compensate. The secret: walls and ceilings near the pit and stage acoustically reinforce the sound off stage so that not one dB is wasted going in a wayward direction or absorbed.

The walls in Seattle were re-angled in such a way that the sound from the stage and pit was directed to the seating areas as early sound reflections in order to support the sound for increased brightness, clarity, and articulation. The ceiling design was complex; it reused the solid plaster coffered ceiling over the rear of the hall but was modified in the front of the hall to support the singers and the pit orchestra, and improve balances between the two.

For the renovation of Kennedy Center Opera House, we focused on the request for ADA seating and to update the hall without degrading the acoustics. We were surprised that much of the flooring was fully carpeted, so we had the main house floor changed to wood directly mounted to the structure for improved resonance, and we quieted all the HVAC systems. In addition to enlarging the pit and adding ADA access there, the soft wall covering (wall paper) was replaced with a harder, flatter material.

The Koch Theatre was renovated last year for the New York City Opera and New York City Ballet. The ballet was happy with the acoustics, but the opera wanted more live-ness, brightness, and reverberation. An ill-advised electronic enhancement system installed in the 1990s was not functioning, and we suggested removing it, along with the carpeting and some wall surfaces.

We made a series of modifications to the sidewalls in the front of the room that improved the brightness of the sound for opera but muffled the sound of the dancers’ shoes on the floor. The intent was similar to McCall Hall: direct sidewall reflections to where they are most needed with the appropriate frequency response and time arrival sequence. While only some of our recommendations could be implemented in the limited time between seasons, the reaction was favorable. We hope to improve the ceiling canopy and other wall shaping in the near future.

Mark Holden is chairman and a lead designer of acoustics at JaffeHolden. He is a member of the National Council of Acoustical Consultants and a Fellow of the Acoustical Society of America. Regarding his work on the renovated Alice Tully Hall at Lincoln Center, The New York Times (January 29, 2009) said, “Musicians hear heaven in Alice Tully Hall’s new sound.”