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Looking Around - On Sound (Part 2): Acoustics

What is acoustics?

Acoustics, broadly, is the science of sound. Some would argue that the term applies solely to the physical properties of sound, but there are many fields within the discipline that focus not on the sound itself, but how it can be perceived, shaped, and applied.

Sub-disciplines such as electroacoustics (the study of electrical applications of sound, such as recording, processing, and reproduction) and architectural acoustics (the focus of this article) inform not only our understanding of how sound works, but also play a key part in shaping the role sound plays in our daily lives. Both have design methodologies every part as rich and nuanced as their sister fields industrial design, interior design, and architecture.

An Inseparable Art

While there are many resources available describing how sound works in rooms, these sources rarely discuss the role acoustics play in the places we live and work.

Architectural acoustics is inseparable from architecture, in that every building has its own unique acoustical profile, hence why many architectural descriptors have a sonic connotation, such as “airy” or “intimate.” Regardless of whether or not a building is designed for sound, its acoustics are shaped by its external environment, intended use, and the architect or builder’s choice of materials, technology, geometry, interior design, and construction.

Most of us understand and expect how sound works in rooms without ever cracking a book on the subject. We know by empirical observation that rooms with many hard surfaces such as stone or wood are much more reverberant (”echoey”) than rooms filled with carpets and heavy drapes. Similarly, we know that a large room with high ceilings is more likely to be reverberant than a small room with low ceilings, and that an empty house is more likely to be reverberant than a house filled with furniture and people.

Public Domain.

This empirical knowledge was the basis of designing for sound from the Greek and Roman amphitheaters up until the late 19th-century. Performance spaces were a result of architectural trial-and-error – successful spaces were imitated or improved, and the unsuccessful spaces often lost to history. Many are surprised that some of the world’s most beloved concert halls and opera houses, such as the Concertgebouw in Amsterdam or Milan’s Teatro alla Scala were constructed before the field of acoustics itself. However, outside of sacred or performance spaces, sound played a minor role in architectural design until the field of architectural acoustics was established by the Harvard physicist Wallace Sabine.

(Sabine was also cute as hell, let’s be real here.)

While trying to solve the acoustical problems of the Fogg Museum lecture hall at Harvard, Sabine discovered a relationship between a space’s volume, the surface areas of the room’s different materials, and how long it took for sounds (of a certain frequency) to fade away within the room (reverberation time). He devised a mathematical equation to explain this relationship. In doing this, Sabine not only quantified the degree to which certain materials absorb certain frequencies, he devised a scientific method that could be used to anticipate certain acoustical qualities of a room prior to its construction. (He later used this knowledge to design Boston Symphony Hall, which is a total banger.)

However, even with today’s technological advancements, architectural acoustics still relies, to some extent, on historical success, trial-and-error, and a pinch of design magic. It’s one of those rare fields that is equally an art and a science.

The Acoustics of Everyday Rooms

It’s not just noise problems that make up our everyday acoustical environments, it’s our architecture, too. During the time when industrialization first made homebuilding affordable for more and more people, common houses had a markedly different sonic profile than they do today, by means of architectural, furnishing and material choices. Socioeconomic factors also played an ancillary role in everyday architectural acoustics, as changes in family makeup and economy drastically shaped the sizes and shapes of everyday housing.

Four Houses

The soundscape of the everyday single family house has changed radically since the time mass housing became common after the growth of the railroad. As plans evolved, so, too, did their sonic qualities. These houses, from 1893, 1915, 1936, and 1963, exemplify how changes in technology, economy, and architecture bring with them changes in the architectural acoustics of our lives.

1893

This Queen Anne plan from 1893 is typical of the period. At this time, neither the indoor bathroom nor electricity were affordable or widespread. Furnaces were becoming more common, but were considered to be upgrades rather than established features in middle income homes such as this one, which was heated by fireplaces and wood-burning stoves.

As we are well aware, privacy and prudence were very important to 19th century society. This is reflected in the home’s closed floor plan, which takes great lengths to separate “public” (e.g. formal parlors & dining rooms) and private (e.g. kitchen, storage, bedrooms) spaces:

The home’s ceilings were 9 feet 6 inches on the first floor, shrinking down to 8 feet on the second floor. The floors were most likely wood, and the walls, plaster. The rooms are modestly sized - the largest room being the parlor, which is 14x14 feet wide.

Acoustically, the home was likely very quiet. These types of homes were commonly built outside the city limits in early suburbs connected either by rail or by streetcar, which made them less susceptible to environmental noise than their urban counterparts, despite the large number of windows. Additionally, because the home lacked electricity, plumbing, or a furnace, internal noise levels were likely low as well.

Despite the home’s tall ceilings and reflective surfaces, the rooms, with the exception of the hallways, probably weren’t very reverberant due to 19th century interiors being heavily upholstered and densely furnished, as explained in great detail by this 1887 promotional handbook on furnishing. Interestingly, the guide insists on “noiseless” carpets for the hall and stairs, which suggests that some design decisions in the 19th century home were acoustically-minded.

1915

A 1915 Bungalow from a Sears Catalog.

This home was designed to be affordable, and hence lacks a bathroom, despite the fact that they were becoming more common. Indoor plumbing was, however, available in the kitchen. At this point, most homes were heated by either gas or steam, and electricity was already present in the more fashionable homes of the decade. While furnaces could occasionally be loud, steam heat was often quieter than even today’s modern electric heat.

Not only are the rooms smaller than their 1893 predecessors, there’s also much less isolation between them, with the exception of the wall shared between the two bedrooms, which is buffered with closets. The lower right bedroom is separated from the living/dining room by a curtain rather than by a formal door, further weakening its sonic privacy.

A large screened porched was often used as a spare bedroom (sleeping porch), or as a place to do the laundry. What is interesting is the bifurcation of the private spaces by one large space. In fact, the open floor plan originated with the early bungalows.

As we can see from the interiors above, this home is much more sparsely furnished than the 1893 home. This is linked to the influence of germ theory, which inspired the idea that home interiors should be easily cleaned, leading to more “hygienic” surfaces in kitchens and less dense fabric furnishings which were thought to harbor germs. Another influence on early 20th century design was Taylorism, or scientific management, which, inspired by the assembly line, aimed to create spaces that were as efficient and “labor-saving” as possible. This thinking eliminated the clutter that was more popular in the 1890s.

Acoustically, this means that certain rooms like the kitchen and sleeping porch were made much louder due to the use of highly reflective, yet “hygienic” materials such as sheet plaster walls, tile, and concrete floors. The only absorptive surfaces in the living/dining room image are the rugs. Even the furniture is less heavily upholstered!

While the interiors may have been louder, the home itself was much more insulated from exterior noise. At this point some form of structural insulation had become standard, as seen above. The “Honor Built” home has double plates over and below windows, subfloors, and an interior wood sheathing. These improvements add an extra layer of protection from exterior and interior noise.

However, at this point the suburbs had become much more dense. Houses such as these were built much more closely together than their earlier counterparts. The automobile had also recently entered the scene, and began to shape the sonic landscape alongside its predecessors, the streetcar and the railroad. Overall, this house was likely much louder than its predecessor. The 20th Century, had arrived.

1936

From Gordon Van Tine Economy Homes.

By the time 1936 rolled around, the car had become more affordable and therefore more present in American life. Both electricity and indoor bathrooms were standard features even in working class homes. However, the Great Depression dampened the construction market, and what homes were being built had to be affordable; thus, they were smaller, more compact, and sparsely ornamented.

In order to save money, this home is condensed into a compact rectangle, making it easier to build than more complex plans. This raises several questions about noise, especially when quieter spaces like bedrooms are directly adjacent to noisier rooms like kitchens and bathrooms, leaving them prone to both airborne and structure-borne noise.

For economic reasons, rooms and windows were smaller than their predecessors, with lower ceilings. Like the previous house, this home was built using more contemporary construction methods, farther from the city in low-density suburbs - this time no longer reliant on the railroad.

Living Room from a 1936 Sherwin-Williams decorating book.

Interior design resources from the 1930s show rooms that were sparsely decorated, possibly to make them appear larger. Despite this, large rugs and heavy drapes were popular at the time. These, coupled with the lower ceilings on economy homes, made the rooms relatively absorptive.

Bedrooms from a 1933 Better Homes and Gardens decorating guide.

Because of better-insulated walls and dense carpets and curtains, these little homes were likely quieter than their predecessors, despite their crammed-together layouts. In fact, they probably sound relatively similar to the average home today, if slightly boomier, as plaster is more reflective than modern drywall or wood paneling.

However, this home sounds remarkably different from the 1915 home, not necessarily because of great architectural differences, but because of the sounds introduced by changing technology: the 60 Hertz hum from electric lighting and appliances, the gurgling or rushing of indoor plumbing, and tire noise from automobiles.

These changes in technology and urbanism lead us to our final home, a ranch from 1963.

1963

Aladdin Readi-Cut Homes. Public Domain.

By 1963, the automobile was ubiquitous, and thus, home construction had entered the era of the attached garage. By this point, the finance constraints that dominated the homes of the 30s and 40s had been alleviated by the booming 1950s. By the time the 60s rolled around, Americans were building bigger houses further and further from the city on wider lots. The ranch allowed for more square footage wrapped in an inexpensive, easy to build package:

(Highly recommend opening this pic in a new tab)

These rooms are far larger than any of the other houses in this post. Low-pitched roofs, shallow ceilings, and load-bearing walls along the middle of the house enabled rooms to be larger without spending a lot of money. It also allowed for more storage, was good for sound isolation between rooms. Centering the plan around a narrow hallway also minimized the surface area through which sound could easily enter a room.

Keeping all of the noisy rooms at one end of the house both clearly demarcated “public” and private spaces and prevented the worst noise offenders (laundry, kitchen, garage) from disturbing folks in the bedrooms. With the exception of the picture window in the living room, ranches often featured small windows, most of which faced the backyard, allowing for better visual and sonic privacy.

Low ceilings and wide walls, coupled with popular surfaces such as high-pile carpet, thick drapery, popcorn ceilings and heavier furnishings like sectionals and sofas made for very absorptive rooms and optimal TV watching conditions. TV wasn’t the only technological change: electric air conditioning and central heat increased both home comfort and background noise. New gadgets and appliances also made the kitchen larger, as they required more counter and storage space. Linoleum, more absorptive than tile, helped quiet kitchen noise.

The ranch was technologically advanced, larger, and quieter than any home before it, which made it a popular choice for almost 30 years. However, the ranch’s low ceilings and squat figure had a pretty damning side effect: they were dark and made people feel cramped.

It’s funny how the ranch and split level generation grew up and started building homes that were equally large if not bigger, but with many more windows, more open floor plans, more reflective surfaces such as granite countertops, and all-stone bathrooms, and with taller ceilings.

Essentially, the McMansion is the anti-ranch, architecturally and acoustically.

After all, A TV in a great room renders dialogue unintelligible, depending if you could hear it over sound coming from the kitchen, or the dining room, or the informal living room, or the lawyer foyer. If only there were a door to close.

Well, folks, that’s it for sound! I apologize for the delay - I got backlogged with freelance work, plus the images took awhile to find and put together. Still, I hope the wait was worth it, and that you enjoyed this detour from our regularly scripted content. Fortunately, McMansion Hell will be running on its usual schedule from here on out, kicking off the new school year with this week’s Oregon McMansion! Have a great rest of the weekend, y’all.

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