A room’s sound is a subliminal quality that we only rarely notice but that produces a visceral reaction. Concert halls are designed to make music sound clear but also to give it body and warmth — qualities that have measurable characteristics. But they are profoundly artificial environments, packed with sound-absorbing audiences, with the sound originating from predictable locations. In rooms that are meant for living rather than just listening, the conditions are more complex. We use our ears to orient ourselves, to gauge an indoor space’s size and purpose.
We listen for clues about how long to stay and how quickly to move. A room that’s too dead and dry can feel enervating, as if happiness had suddenly been pulverized into a layer of dust. A space that’s too live, where a sound goes slamming against its own reflection, can be disorienting. Being unable to tell where a noise is coming from feels like being dazzled by glare, like being the victim of a hostile act. We tend to react exactly wrong in such aggressively reverberant rooms: Instead of all dropping our voices to an intimate murmur, we raise them to compete, which only adds to the murk. That’s why in so many restaurants with low ceilings and concrete tables, one diner with a hearty laugh can tip a pleasant hum into a group roar.
To get a better appreciation of how we experience big public rooms with our ears, I asked Raj Patel, an acoustical engineer at the global firm Arup, to join me in the Main Concourse of Grand Central Terminal, one of the most acoustically pleasing spots in New York. We talked quietly beneath the zodiac ceiling far above, enveloped by a soft cushion of chatter and clicking feet. Occasionally a spoon clinked against a cup on the mezzanine level a block away from where we stood. The noise ricocheted off the café’s marble wall and sped toward us, clear and uncontaminated by echoes, so that I instinctively turned toward its source. That crystalline ping mixed with sounds that drifted up to the ceiling and fluttered back down in a soft haze. Or else they wandered off through archways, got trapped beneath balconies, or scattered against the ornamental foliage. […]