The Voice of the Building

Every room has a voice. A concrete stairwell hums differently from a carpeted corridor. Sarah Chen’s job is to listen to buildings before anyone else moves in.

Learning to hear architecture

Chen trained as an architect before becoming interested in acoustics through a project that, she explains, went wrong in a way nobody could immediately diagnose.

“We had designed what looked like a very good open-plan office. The right proportions, good materials, natural light. When people moved in, they were exhausted after two weeks. Nobody could concentrate. There was no obvious reason.”

The reason, eventually, was reverberation. The hard surfaces created a sustained background noise level that the brain had to continuously filter. It was not loud enough to be noticed consciously, but loud enough to be metabolically expensive. The building was draining the people inside it.

“That is what got me interested in the invisible aspects of space. The things you feel before you can name them.”

The materials of silence

Acoustic design is not primarily about soundproofing, though it includes it. It is about managing how sound behaves in a space - how long it sustains, from which surfaces it reflects, where it pools and where it dissipates.

Hard, flat, parallel surfaces create flutter echo: sound bouncing back and forth between walls, audible as a metallic shimmer after a sharp noise. Soft and irregular surfaces absorb and scatter. The ratio between absorption and reflection determines how alive or dead a room feels.

“Most people think acoustics is about concert halls,” Chen says. “But the work that matters most is in schools, hospitals, offices - the places where bad sound makes people tired without knowing why. Those are the buildings that touch everyone.”

The Copenhagen library

Her current project is a new library in Copenhagen, designed in collaboration with a Danish practice whose name she is not yet permitted to disclose. The brief was precise in its imprecision: quiet enough to think, alive enough to feel inhabited.

“Those are in tension. Absolute quiet is not comfortable in a public building. There is a point of excessive deadness where a room feels anxious rather than peaceful. You need some life - ambient sound from outside, footsteps, the sound of other people being present. What you want to remove is the intrusive sound, the speech intelligibility problem, the building’s own noise.”

The solution she is developing involves a ceiling composed of suspended wooden baffles at varying angles and depths, which scatter rather than absorb high-frequency sound. Combined with a raised floor containing acoustic mass, the effect should be a room that registers as quiet without feeling sealed.

Listening as a method

Chen’s practice begins every project with what she calls a listening session - visiting the site before any design work begins and simply attending to the sonic environment.

“What is already there? What does the neighbourhood sound like? Where does traffic come from, at what times? What will change seasonally? These things are usually invisible to the design process until it is too late.”

She describes listening to a site as a form of fieldwork, similar to the ecological surveys that responsible developers commission to understand what they are building into. Sound is a dimension of place that architecture has historically treated as an afterthought. She would like to change that.

What we hear without knowing

The interview ends in the street outside Chen’s office, a narrow passage between two brick buildings. She pauses before answering my last question, and for a moment I notice what she is presumably always noticing: the particular sound of this specific place, the way the buildings channel and reflect the noise of the city into something unlike the street I came from.

“We don’t know what we’re hearing,” she says finally. “We just know how it makes us feel. That’s the design problem.”