Step into the underground concourses of New York’s Penn Station and you might just feel an uneasy sense of claustrophobia that’s hard to explain. Stroll across the hardwood floors at the National Gallery of Art in Washington DC and a sense of calmness might descend on you. Why? Each of these buildings has its own unique voice – the way sound behaves in the structure.
Think of the way whispers travel in the circular dome of St Paul’s Cathedral in London and how the curved ceiling of the lower floor of Grand Central in New York can carry voices. Then there is the satisfying click of heels walking through an deserted hallway or the way your bathroom makes your singing sound better. This “aural architecture” can have a profound effect on the way you experience a building. (Read about how you can navigate a room using clicks alone)
“Aural architecture is about how we listen to buildings, the sound within buildings and how we react to them,” says Trevor Cox, an acoustic engineer at the University of Salford, in Manchester. Even though we primarily navigate our way through the world using our eyes, it seems our ears are constantly picking up information from our surroundings that unconsciously alters how we feel about a space.
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Though they emit no sound, you can hear an empty room. You can find out if it has low ceilings and where its walls are just by the way sound reflects off these surfaces. Think of the echoing noise the click of a heel makes on a marble floor as opposed to the muffled padding from someone walking on thick carpet.
“You can walk into a room blindfolded and you can probably hear if there’s a carpet on the floor without stepping on it,” says Barry Blesser, a former electrical engineer at the Massachusetts Institute of Technology, who coined the term aural architecture. “We can hear all kinds of things. We just don’t pay attention.”
Even quiet sounds can be carried long distances in an indoor space like the whispering gallery at St Paul's Cathedral (Credit: Alamy)
We have probably all been in a building that sounds wrong. Dingy offices where noise rattles uncomfortably between the floor and the ceiling, old houses where the creaks and groans of ageing floorboards carry hauntingly from room to room, train stations where public announcements reverberate until they are indecipherable.
There is growing recognition that buildings not only need to be functional and aesthetically pleasing, but acoustically satisfying as well
While it may be hard to put a finger on why, these places can feel instinctively uncomfortable to us.
Now, there is growing recognition that buildings not only need to be designed to be functional and aesthetically pleasing, but acoustically satisfying as well – leading some architects and engineers to rethink how spaces are shaped and the materials they are made from.
Scientific research suggests they are wise to do so. Noisy work and home settings have been proven to annoy people, and noise annoyance itself has been linked to depression and anxiety. Furthermore, issues concentrating in the workplace due to office noise and intermittent noise has been found to significantly reduce human performance.
But the way sound interacts with a building’s physical structure can also significantly alter our moods and emotions. For instance, studies show that living in crowded housing can cause a feeling of helplessness. Rooms with loftier ceilings encourage more abstract thought as people feel more free in such airy spaces. Consider the emotional impact of a structure like the Hagia Sophia, Istanbul’s famous former cathedral and mosque, which now houses a museum. Built nearly 1,500 years ago, its domed interior and marble floors and walls can elevate human chants into ethereal sounds that seem to emanate from the depths of the ocean and create a feeling of exaltation in the listener.
The Hagia Sophia in Istanbul, Turkey, alters the sound produced inside its walls so profoundly that it is capable of 'conjuring up the divine' (Credit: Getty Images)
“It has a sonic aesthetic that is capable of conjuring up the divine,” says Bissera Pentcheva, an expert in Medieval art at Stanford University, who investigates the spiritual aspects of Medieval structures. “It takes human speech and chant beyond the register of human language.”
Mainstream architecture typically considers a building’s sonic voice only in the construction of concert halls, where acoustic perfection is key. The idea that you can take this a step further, and have a building itself act as a sort of musical instrument that envelops people, that’s capable of inducing feelings of tranquility, exhilaration, tension or even a trance-like state is unusual. However, it isn’t unknown.
The way sound interacts with a building’s physical structure can also significantly alter our moods and emotions
When a person’s voice hits a frequency of 110Hz in the “Oracle room” of the 5,000-year-old Maltese underground temple Ħal Saflieni Hypogeum, it comes alive. It’s as if more voices join in, the sounds intensifying from every direction until it can be literally felt as a tingle through the skin. A neurological study that examined how the acoustic properties of ancient structures influenced brain function found that briefly listening to a tone of 110Hz reduced activity in the brain’s language centers and shifted activity to the brain’s emotional areas.
If the acoustics of space tuned to amplify just a single tone can affect us so profoundly, what effect might a room that amplifies many have on our consciousness? Shea Michael Trahan, an architect at Trapolin-Peer, is using cymatics – the way surfaces vibrate – and three dimensional printing technology to answer this question. He is creating 3D structures that he hopes could be scaled up so that you might be able to walk in and sing a B flat or a C major to make the building resonate, or “sing” back.
Human voices reflect off the marble floor and domed surfaces inside the Hagia Sophia to that can have a profound affect on those listening to it (Credit: Getty Images)
“What I seek to do is to create spaces that isolate a single tone much like the Matrimandir, a golden geodesic dome used as a meditation space, focuses a single ray of light,” says Trahan. “The hyper-reverberance is actually the architectures’ gift back to the observer in that it is using their sound and extending it as much as possible to intensify or heighten the experience.”
There is the possibility this could have a use that goes beyond creating spaces that are enjoyable to spend time in. These sonically interactive structures could function as immersive sonic therapy rooms for existing sonic therapies for PTSD, depression and Parkinson’s disease. Vocalists could even use them to tune their voices to hit tones with precision. (Read about how hospital noise can undermine patient safety)
“When space acts as an instrument, the space can tune you,” says Trahan.
Susan Magsamen, executive director of the International Arts and Mind Lab at Johns Hopkins University in Baltimore, is taking part in a multidisciplinary project that aims to create an entirely new type of healing space for children waking up from traumatic brain injuries. Scheduled to be built later this year, the Kennedy Krieger Children’s Hospital’s “Sensory care room” will customise sounds, such as a mother’s voice or a song, favourite smells, temperature and light to the individual child, in a room that feels like a cocoon, to help children wake up faster and better.
Penn Station in New York would not win any prizes for beauty but it is also acoustically quite an ugly space as well (Credit: Alamy)
Michael Fowler, a member of the audio communication group at the Technical University of Berlin, approaches aural architecture differently. He is inspired by open spaces that have unique sonic features, such as such as Japanese gardens that feature dry stone waterfalls that tinkle like real waterfalls, by clever positioning of water features out of sight. He studies what he calls “exemplary” sound spaces in an attempt to find out what makes them special, be it geometric forms or the arrangement of materials in a room. He wants to use this to create an algorithm or a computational routine, a sort of digital aural archetype, which architects can use when designing buildings or other public spaces.
“Using this, you can produce this type of exemplary space, and they may exist in very different media, but their actual structure, the relationship between sound and space, will be common between all of them,” says Fowler. “Though when you abstract them out, they may look completely different.”
Buildings, however, don’t exist in isolation. They form towns and cities where there is no escaping the roar of traffic, the boom of construction work, blaring nightclubs and the piercing wail of sirens and alarms. Around 83 million people in Europe live in areas where sound pressure levels are above recommended levels, says Fowler.
New technologies and new types of materials could help. Augmenting existing structures with vibrating façades, for instance, could potentially cancel out noise by exploiting the physics of interference. Produce a sound wave at the right frequency and wavelength, and it will counteract the sound waves of an unwanted noise.
The Oracle room at the ancient Ħal Saflieni Hypogeum resonates when voices inside hit a specific frequency (Credit: Getty Images)
“In the future it may be possible that if you lived near an airport, as soon as you stepped within a couple of metres near the building, the sound of the airport disappears because of the active noise cancellation from the whole building,” says Fowler.
But if it’s not possible to get rid of the noise, why not embrace it? Make traffic noise musical, for instance. In 2016, Jordan Lacey, a research fellow at RMIT University, Melbourne, created a noise transformation installation that picked up the traffic noise adjacent to a park via microphones, mixed it with musical sounds and played them back through loudspeakers in the park area. It had people living in nearby housing, wanting to sit on their balconies, instead of shutting themselves off from the outside.
The conceptual MIX house, designed by Karen Van Lengen, an architect at the University of Virginia and her colleagues, envisages concave windows which act as “sonic dishes” that can be angled in different directions to capture sounds from the surrounding neighborhood. Homeowners can then mix these sounds through an audio system to create musical compositions where a dog barking or a child shouting becomes an ambient soundtrack.
We didn’t evolve listening to the hum of air conditioners or screeching tires
But while it’s one thing to invite the noises of our surroundings into our homes in new ways, is it possible to escape them altogether? Architects tasked with designing future cities are more aware now of the need for quiet and nature sounds in city soundscapes. After all, we didn’t evolve listening to the hum of air conditioners or screeching tires. Lacey believes it’s important to have aural architecture installations nested throughout cities to create a network of “sonic ruptures” – places where existing urban noises are transformed with the use of technologies and landscaping to create unique soundscapes that are aimed at enriching people's experience of an area.
“It’s all very well to complain about the noise of the city and say it has to be more like nature but what about all the people who don’t have access to that?” says Lacey. “We can design these sonic environments to give people not the experience of nature because it isn’t nature but some sort of urban equivalent. Think about how big some of these cities are going to be in 50 years time.”
The Elbphilharmonie concert hall in Hamburg has a 'skin' designed with the help of algorithms to improve its acoustic characteristics (Credit: Getty Images)
Thanks to virtual reality systems, architects are beginning to listen to how the spaces they design might sound like through “auralisations” of structures using acoustic modeling software like Odeon. Such auralisations are used to prevent sound transfer between spaces and make design decisions such where to place absorption, diffusion or reflective surfaces.
“Architects are able to hear what their designs sound like and where required, adapt them to improve the acoustic response,” says Naomi Tansey, an acoustics consultant at the engineering firm Arup. Going further, auralisations enable the creation of unique spaces, such as the central auditorium in the Elbphilharmonie concert hall at Hamburg which sports a stunning algorithm-designed “skin” made of 10,000 gypsum fibre acoustic panels, which help create a balanced reverberation.
Others such as University of York’s Mariana Lopez study acoustic heritage with the aid of software. “Auralisations are used to allow us to listen to spaces that either no longer exist or have changed throughout history,” says Lopez. Aside from preserving acoustic history, these auralisations are important when restoring historic structures as the materials used can affect the acoustics significantly.
Whisper into one of the corners in the whispering gallery under Grand Central Station in New York and the domes will carry voices to the other side of the room (Credit: Alamy)
But it could still be some time before our homes, offices and cities become pleasing to the ear as much as they are to the eye.
“Very little in the language of bureaucracy or policy says that we need to design for this,” says Lacey. “We design to minimum benchmarks.”
If we could start to see sounds like Fowler, who views them as a clay-like material, a thing to be shaped, formed and composed, it could open up truly exciting possibilities in the way we construct our acoustic environments. "If you were knowledgeable about sounds, how it was linked to space and how to change its behaviors,” says Fowler, it could expand our experience of the built environment around us.
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