The following is an excerpt from the essay Acoustic Ornament. The full essay is available in a digital edition.

Place an object in a space, and it will change the sound of that space.

Changes of enclosure shape of any kind will modify acoustic behavior.

Sound does not distinguish between objects added and surfaces deformed.

It does not distinguish between that which is intentionally acoustic and that which is not. A room with a floor shaped to express the form of a chair will sound the same as a room with a chair placed as an object.

Three-dimensional ornament influences the sound of spaces.

It usually increases the surface area of the enclosure and therefore quickens the decay of sound within. When architecture shifted away from ornament in the late nineteenth and twentieth centuries, acoustically-dissipative spaces shifted toward the more reverberant planar benchmark. Sound sustained longer in the spaces of intersecting planes than it did in the more complex enclosures that preceded them. Manufacturing technology pushed this even further by giving rise to nearly-true surfaces; a planar wall of machine-made gypsum board is more flat than one of hand-applied plaster. The acoustically-significant subtle variations of thecraftsperson were lost, and architecture locked into the planar benchmark.

The loss of ornament left a sonic void, into which a new type of applied architectural product arose: acoustic panels.

This was partially in response to the need for acoustically dead environments for new audio broadcasting and recording technology, but it also acoustically corrected for the loss of complexity in room shaping. Manufacturers offered architects an additive option, the purpose of which was to shift rooms in the direction of quicker dissipation. Manufacturers also recognized that products added cost and an unwanted visual impact, so they worked to maximize the acoustic effect of every square meter of surface while hiding, as well as they could, the visual expression of the complexity of form this required. This was the moment sound and light separated within architecture. If the acoustics of a room needed to be improved, it was to be done with minimal visual impact.

Manufacturers vied to be the sole solution rather than a mild contribution to the shape of spaces. Acoustic absorption became engineered and efficient. The innate acoustic influence of the non-acoustic—the integral surfaces, ornament, objects, furniture, textiles, plants, and people—began to be forgotten. Acoustics became equated with the selection of a product. An entire field of expertise simultaneously arose which was dedicated to understanding sound in spaces; its work centered on which products, and how much to use, to treat each space. These experts were, and still are, employed on only a small fraction of projects, and their knowledge has yet to merge into architecture. Acoustics is something outside of architecture, to be minimized if not avoided altogether.

Some manufacturers produce acoustic products that express visual complexity. Custom solutions driven by the architect can be found. This is a recognition that objects have acoustic influence, and acoustic geometries have visual implications, but composing the sound of rooms with the subtle acoustic effect of every part of the interior is the future that has yet to be realized.

Material limits shape and scale.

In acoustics, material should mean the substance, like glass or concrete, and not configuration, such as fiber glass or concrete block. Some materials can take forms that access any category of acoustic behavior: transmission, focus, reflection, diffusion, and absorption. These materials expose a continuous spectrum of geometric and acoustic possibility. The enclosure in the thought experiment morphs from one condition to the next without material changes or a distinction between that which is acoustic and that which is not. Evidence for the importance of form is empirical.

Any material when shaped into felt of ample depth and density will absorb, when made into peaks and valleys will diffuse, and when made into flat sheets will reflect.

Glass is common in planar form, which acts as a flat, reflective sonic mirror. Glass can be perforated to allow sound to pass through unimpeded. It can be cast, bent, or slumped into three-dimensional forms that focus or diffuse sound energy. The atrium at the Charles H. Wright Museum of African American History in Detroit is a space that focuses with glass; the acoustic wonder of its visually transparent dome can be experienced by standing at the center of the floor and making any sound at all. If glass is drawn into fine fibers and woven or needled into blankets, it becomes absorptive to sound.

Glass spans the range of acoustic properties traversed in the thought experiment, including the underexplored regions that lie between established moments of acoustic behavior. Resin, metal, stone, and frozen water are just as acoustically versatile. The Great Lakes Region offers the acoustic range of frozen water, from specular reflections off expansive, flat surfaces of ice, to the diffusion of ice formations, to the quiet absorption of newly-fallen snow.

Read the full essay here.