Minus Twenty Decibels

A man sits in the dark in Minneapolis, in a chair, because standing has stopped working. The room around him was engineered to remove the world from his ears, and it worked. What remains is the percussion of his own heart, the bellows noise of his lungs, a stomach conducting its slow chemistry at a volume that seems, in context, rude. He is the loudest object present. He will not last the hour.

The room belongs to Orfield Laboratories, and its construction is an argument conducted in materials. All six sides are lined with fiberglass wedges more than three feet deep. Behind those sit double walls of insulated steel, and behind those a foot of concrete. The assembly absorbs 99.99 percent of the sound produced inside it. When Guinness certified the chamber in 2004 it measured minus 9.4 decibels, a figure that held the record for the quietest place on Earth; by 2012 the same room measured minus 13.¹ A quiet bedroom at night measures about 30.

The negative number needs a word of explanation, because it sounds like a marketing artifact. The decibel scale used for hearing is anchored at zero, and zero is roughly the softest sound an average human ear can detect at the pitch where ears are most sensitive. Zero is a census result, not a physical constant. A room at minus 9 has a background quieter than the threshold of the instrument the scale was named after. Nothing in the room is broken. The room has simply been carried below the level at which hearing, as a sense, reports anything at all.

And yet people inside it hear a great deal. Given nothing external to process, the ears raise their own sensitivity, the way eyes adjust to a darkened theater, and the body files its reports at the new gain. Steven Orfield, the laboratory's founder, puts the mechanism plainly: the quieter the room, the more things you hear, because in an anechoic chamber you become the sound.¹ Orientation degrades along with the quiet. Balance and movement lean heavily on incidental sound, the small echoes of footsteps and shifting weight, and with those cues withdrawn the only reliable way to stay in the room is to sit down and stay sat. The longest reported stay is 45 minutes.

The chamber's first famous visitor arrived with better questions than most. In 1951 the composer John Cage entered an anechoic chamber at Harvard expecting to hear nothing at all. He heard two sounds, one high and one low, and asked the engineer in charge what they were. The high one, he was told, was his nervous system in operation. The low one was his blood in circulation. Cage drew the conclusion the room had been built to make unavoidable: until he died there would be sounds, and they would continue after.²

The following year, in Woodstock, New York, the pianist David Tudor sat at a piano, closed the lid, and held still for four minutes and thirty-three seconds, opening and closing the lid to mark the movements. The audience, denied the performance it had paid for, supplied one anyway: shuffling, coughing, the weather outside, people leaving. 4'33" is usually filed as a stunt or a joke about modern art. It is better read as lab equipment. Cage had built a frame that converts any room into the Harvard chamber's public cousin, a device for hearing what a place sounds like when nobody is performing in it, including the audience itself.

The engineers kept digging after the composer left. In 2015 a chamber in Building 87 on Microsoft's campus in Redmond measured minus 20.6 decibels, taking the record from Minneapolis by a wide margin.³ The room rests on its own foundation of springs, so the building's vibrations arrive nowhere near it. It exists for an unglamorous reason: Microsoft needed somewhere quiet enough to hear the noises its own devices make, the small mechanical sounds of hardware, so products could be measured against silence instead of against the room doing the measuring.

There is a floor under this pursuit, and it is close. The random thermal motion of air molecules, Brownian motion, produces a pressure flutter measured at roughly minus 23 decibels. Air itself is faintly audible in principle, and below that flutter there is nothing left to remove except the medium. The Redmond chamber sits about two and a half decibels above the limit set by physics for any room that contains air and a person breathing it. Seventy years of engineering, from Harvard's chamber to a spring-mounted vault in Redmond, bought the distance between an ordinary quiet room and the edge of the possible, and nearly all of that distance was traveled in the last two decades of the chase.

At these levels the measurement problem inverts itself. A device under test in Redmond is being compared against an engineer who breathes at about ten decibels, whose heart valves open and shut on schedule, whose joints click. The device is the quieter party by a wide margin. It is a good chamber for its stated purpose, since microphones do not have stomachs. But a human being who walks in to experience the record is in the position of a lighthouse keeper touring a lighthouse: the apparatus is not the attraction. The apparatus reveals the keeper. Orfield's chamber gets used to test heart valves, CPAP machines, and cell phones, and NASA has used it to prepare astronauts for the silence of space. Every one of those uses treats the room as a reference. The tourists are the only visitors who mistake it for the exhibit.

The same subtraction is now available at retail. Noise cancellation sells the first decibels of the descent to anyone with headphones, and quiet is printed on appliance boxes as a specification beside capacity and wattage. Silence retreats charge by the night for what a concrete box in Minnesota delivers by the minute. None of these products reaches the floor, and reaching the floor turns out not to be the desire anyway. The desire is a volume knob on other people. The chamber has no knob. It is egalitarian in the one way nobody requested: it subtracts the visitor's noise at exactly the same rate as everyone else's, and hands back whatever is left.

The record in Minneapolis still stands where it stood. Forty-five minutes, seated, in the dark, listening to a body that had been running its machinery at full volume all along, in every room, under every conversation, beneath every piece of music ever played in it. The door opens. The corridor arrives all at once: ventilation, footsteps, a voice down the hall, the building clearing its throat. It sounds like an orchestra tuning. It is the world, at thirty decibels, resuming.