Making Sense of Sound: The Science Behind Orchestra Hall's Flawless Acoustics
One of the most common refrains among DSO fans, musicians, staff, collaborators, and insiders is that Orchestra Hall is “acoustically perfect” or very close to it.
For example: “Orchestra Hall is like a friend giving your notes a hug as you play,” says the DSO’s Bill Lucas, trumpet. Former principal guest conductor Peter Oundjian called it a “miracle;” Yo-Yo Ma declared it “one of the wonders [of the] music world.”
The hall’s superb sound is touted so widely – and so frequently – that it’s something of a mantra; people just know it’s good, in the same way they know that Beethoven went deaf or that the Lions wear Honolulu Blue. But how perfect is the sound really? And what factors contribute to the supposedly excellent acoustics for which Orchestra Hall is so praised? Anyone with a fine ear can declare that the hall sounds great, but it takes an acoustics expert to explain how and why.
Enter the Detroit office of the German company HEAD acoustics, a leading provider of test systems for evaluating and troubleshooting sound quality. HEAD’s work in Michigan mostly relates to automotive interiors, but their futuristic technology is a perfect fit for decoding Orchestra Hall’s top-notch sound. Last spring, HEAD placed five measurement devices – shaped like human heads – throughout the auditorium and onstage to gather data during a DSO rehearsal. At the September 2019 Centenary Sound Lab event, they brought a new toy: the HEAD Visor, which allows users to visualize how sound interacts with the hall’s interior.
After reviewing HEAD’s analysis and consulting with other experts – including Jaffe Holden, a leading acoustics firm that has worked with the DSO for decades – the results are in.
Shape and Size
Like many other theaters lauded for their great acoustics, Orchestra Hall is built in the “shoebox” style – a rectangle, essentially, though it has slightly curving walls that some experts call “lyric” style. Shoebox halls tend to allow for a great balance of direct sound (which leaps from the stage in straight, uninterrupted paths) and indirect sound (which bounces and reflects before dying down), especially compared to “fan” style halls that gained popularity in the middle of the 20th century because they offer better sight lines.
Orchestra Hall is also sized beautifully – not too big, not too small. Cramped halls allow indirect sound to bounce around too much, creating noise; expansive halls allow sound to die out before it can reach the furthest corners.
Two of Orchestra Hall’s “secret weapons” are located directly above and below the stage. Architect C. Howard Crane designed the building with flexibility in mind, so he included two features that would aid in the production of operas and plays: a fly tower high above the stage, and an empty space called a “trap room” (because it’s accessible via trapdoor) below.
While these features are rarely used for their original intended purposes, they greatly improve the “warmth” of Orchestra Hall’s sound. This is because low-frequency bass sounds (like those produced by cellos, basses, and timpani) have time to resonate above and below the stage before being pushed out into the seats, which makes them sound richer and more blended.
As an added bonus, the resonance created by these two features allows musicians onstage to hear each other much more effectively – an extremely rare quality, even among concert halls that sound great from the auditorium.
No Bad Seats
Another result of Orchestra Hall’s size, shape, and special features is that the sound is excellent in virtually all areas of the auditorium – even seating sections underneath the balcony and boxes, which usually suffer from poor acoustics in similar theaters.
Analysis by HEAD acoustics proves what many DSO fans have known for years: that every seating section sounds great, but some areas have unique “flavors.” And amazingly, the differences are extremely slight. Visual spectrograms of sound samples collected throughout Orchestra Hall (view image gallery above) reveal only minor variations, which means that the sound in a supposedly “good” area of the Hall is all but indistinguishable from the sound anywhere else.
The X Factor
Other seemingly negligible details also account for Orchestra Hall’s spot-on acoustics, including the hardness of its plaster walls and the particulars of its ornamentation. But as Mark Stryker – former Detroit Free Press critic and the closest thing to a professional Orchestra Hall fan as one can be – puts it, “formal analysis has its limit.” Pore over the details all you want, but sometimes you have to chalk it up to the term we stole from the French: je ne sais quoi.
Another term works well too: magic. Yes, it’s a cliché. But the beauty of a magic trick isn’t that it makes us believe in magic – it’s that it makes us say how did they do that?
Experience the sound of Orchestra Hall2019-2020 Classical Series