In March 2022, the city of Ghent installed sound-level monitors in the Korenmarkt, the stone square at the center of the old town. The monitors measured 47 decibels at 7 AM. By noon the number was 73. By evening it was 81. The monitors were placed for a noise-reduction initiative — complaints from residents about nightlife, the usual. The data did exactly what it was supposed to do. It told the city how loud things were.
It told the city nothing about what the square sounds like.
I have stood in the Korenmarkt. I know the difference between the morning version and the noon version, and it is not a matter of volume. At 7 AM the stone gives back everything. My footsteps arrive twice — once from my shoes, once from the church wall forty meters east. The square is enormous at that hour. I can feel its edges. By noon the same square has collapsed. Not louder. Smaller. The bodies absorb what the stone used to return. The spatial information that let me walk its diagonal without a cane at dawn is gone by lunchtime.
A decibel meter cannot distinguish between sound that carries spatial information and sound that destroys it. It measures pressure. Not meaning.
In Helsinki, something different happened. The city’s 2019 acoustic plan for the Oodi library — designed by ALA Architects — used reverberation time as a design parameter from the start. Saija Hollmén, one of the partners at Hollmén Reuter Sandman who consulted on acoustic accessibility for several Helsinki public buildings, said something I have not been able to forget. She told a 2020 seminar at Aalto University: “We designed for the ear that is doing the most work.” She meant blind visitors, partially deaf visitors, neurodiverse visitors. The people for whom acoustic clarity is not ambiance. It is infrastructure.
The Oodi’s main hall has a reverberation time of 0.6 seconds. This is a number. But it is a number that describes something I can feel the moment I walk in. My voice comes back to me clean. One reflection. No smear. I know where the walls are. I know where the ceiling changes height. The room tells me its own shape.
You might say: isn’t that just good acoustic design for everyone? It is. That is the point. The people who need it most are the ones who can tell you whether it works. Everyone else benefits without knowing why.
Georgina Kleege wrote in More Than Meets the Eye that blind people are often better critics of visual culture than sighted people, because we have had to study what sighted people take for granted. The same holds for acoustic space. I do not experience reverberation as a number on a specification sheet. I experience it as the difference between a room that tells me the truth and a room that lies.
The Ghent monitors produced data. The Helsinki designers produced knowledge. Both used numbers. One set of numbers described a symptom. The other set described a relationship — between a surface and a body, between a wall and an ear.
The instrumented evidence that acoustic design advocates have wanted for years now exists. Absorption coefficients, reverberation standards, frequency-weighted clarity indices. The numbers are real. I am glad they exist. They make it harder for procurement committees to say “we’ll consider acoustics later,” which in practice means never.
But here is what the numbers cannot carry. The moment I walk into a room and know — before thought, before analysis, before I have taken three steps — whether this room was designed by someone who understood that sound is not decoration. It is the room itself. For me, it is the walls. It is the ceiling. It is the distance between my body and the door I have not yet found.
A 0.6-second reverberation time and a 2.4-second reverberation time are both numbers on a page. One of them is a room I can read. The other is a room that has swallowed its own name.
This article was inspired by Acoustic ecology measurement standards in urban design from acoustics.culture.