The Sound of Silence

How many crazy gizmos are needed to achieve your optimum sleep environment?

On winter nights, the white-noise app on my phone is tuned to Air Conditioner: a raspy, metallic whir that sounds like the mechanical noise that might echo deep inside the ductwork of a huge commercial building. (Among the app’s other offerings are Dishwasher Rinsing, Crowded Room and Vacuum Cleaner.)

It lulls me to sleep nonetheless, because it blankets the din in my apartment (the ragged snore of a roommate; the clanking of the steam radiator; the cat’s skidding pursuit of something only he can see).

It may also soothe because it replicates an early sound environment, probably that of a Manhattan childhood, though perhaps it suggests something much, much older. Some sleep experts note that babies, their ears accustomed to the whisper of the maternal circulatory system and the slosh of the womb, sleep better accompanied by a device that mimics those familiar whooshings.

My app is but one note in the mighty chorus of white-noise generators, an exploding industry of mechanical and digital devices; apps and websites, and Sonos and Spotify playlists that grows ever more refined, as if to block out the increased rate of speeding, the wrecks, on the information superhighway. 

Car Interior? Oil Tanker? Laundromat? These ballads are in the vast soundscape library created by Stéphane Pigeon, a Belgian electrical engineer, and ready to play on Mynoise.net, a sound generator he put online in 2013 that now has one million page views each month. It’s a nearly philanthropic enterprise, as it runs on donations. “I have enough stress,” Dr. Pigeon said.

Reddit, among other message boards, offers D.I.Y. white-noise hacks for light sleepers, shift workers and tinnitus sufferers. Rough up the blades of a box fan with a box cutter, suggested Christopher Suarez, a field service technician from Riverside, Calif., whose wife is an insomniac, on one captivating thread there.

The first so-called domestic white-noise machine may have been built in 1962, by a traveling salesman whose wife grew used to the air-conditioners in the motels they frequented and was unable to sleep at home.

But white noise was identified by engineers as early as the 1920s, Dr. Pigeon said, and used as a test signal because, as he put it, “it’s the sum of all the audible frequencies in equal proportion in a single sound. It’s so named because of its analogy to light, which turns white when all visible frequencies are summed up into a single beam.”

Back home in his garage, Jim Buckwalter, the salesman, set a turntable and a fan blade into a dog bowl insulated by some foam, and invented the Marpac Sleep-Mate, now called the Dohm ($40 on Amazon), a gizmo whose popularity grew by word of mouth and became a favorite not just of light sleepers, but also of psychotherapists, the legal and medical community, and others seeking to mask confidential conversations. (Nothing says 1980s-era Upper West Side analysis like the whispery hiss of a mushroom-shaped Dohm.)

Sound purists adore it, because its mechanical whirring is closer to truly random and contains no loop, as many digital versions do.

Blocking the Bullfrogs

Fred Maher is a veteran music producer and drummer who works as an audio engineer and audio-quality tester. He has what are considered golden ears, meaning he is an expert listener who can spot audio errors in music, film and television content. He also suffers from tinnitus, a condition he soothed for years with machines like the Dohm. (That device is now in the bedroom of his 6-year-old daughter, Ruby.)

White noise, he wrote in an email, “is one of the first things we hear from our first moment of existence, in utero (not the Nirvana album). It’s what you hear in a seashell, kind of. The seashell is a mechanical filter that focuses and amplifies ambient noise.”

Sleep is inherently dangerous, said Rafael Pelayo, a clinical professor of psychiatry and behavioral sciences at the Stanford Center for Sleep Sciences and Medicine. This is why we are wired to sort sounds as we sleep, he said, to differentiate the threats, or a baby’s cry, from more benign noises.

“How can a mother feed her baby if the ability to wake up is not wired into our brain?” Dr. Pelayo said. “The thalamus needs to decide if a noise is worth informing the cortex. There’s a concept in sleep called the arousal threshold — it’s the stimulus you need to go from a deep sleep to awake. It can be a loud noise, like a garbage truck, or something soft, like your partner saying, ‘Honey, I think there’s a burglar in the house.’ The idea of a noise generator is to raise the background noise so you don’t notice the sounds that aren’t worth your attention: a snoring partner or the hotel elevator.”

Dr. Pelayo is on the board of Adaptive Sound Technologies, which makes Lectrofan ($50 on Amazon), a digital, but nonlooping, version of the old analog noise machines, but he stressed that Stanford does not endorse products.

There is no data that suggests a white-noise machine alters the frequencies of the brain, said Param Dedhia, the director of sleep medicine at the Canyon Ranch in Tucson. “But we can show that if you make a loud sound, you can affect your response to that with a noise machine. It’s called auditory masking.”

Dr. Dedhia described its effects as a sound bubble, “a force field of sound such that a noise has to be much stronger to break through.” Dr. Dedhia has deployed Marpac Dohms in the bedrooms at Canyon Ranch, and also in his home, because the pool there draws an army of bullfrogs after dark. Their nightly chorus drives him bananas.

“Oh, my friend,” he said, “it sounds like someone dying. I used to get my hose and spray them off the sides of the pool, but they soon were on to me, and after a while just hopped back on. So now I have my humidifier running, and the white noise right next to the bed. It’s my sound bubble. We don’t have to have a bug or pill for every ill if we can soothe ourselves. It’s a skill, it really is. If we could all self-soothe, it would make it easier to handle other chaos.”

What is noise, anyway? Dr. Dedhia likes this definition, from the authors of a sleep study: “Noise is defined as unwanted sounds that could have negative psychological and physiological effects.”

Noise is terribly subjective. There are those who love the croak of a bullfrog, and are soothed by the snores of their partner because it means they are close. Dr. Pigeon allowed that snoring was particularly tough to mask, given its locality (next to your head) and unpredictability (your ears crane for the next growl or explosive sigh).

“You must convince yourself the sound of snoring is beautiful,” he said. “I have some people who asked me to put snoring on the website because they are used to sleeping with a partner snoring, and when that partner is gone — traveling or divorced or dead — they miss that sound.”

“I have some snoring hidden in one of the generators,” he said. “It’s called Berber Tent. It’s an attempt to take you on a nice story. You are in the desert on vacation and it has been a very warm day and you are all snoozing in the tent together while food is prepared. You can hear the breeze, and the tent flapping and the sound of a man snoring. I didn’t set out to do that, but I always am waiting for opportunities and I was on a trek and I heard it and I taped it. I think if you imagine a beautiful young Berber sleeping next to you, it will change your mind.”

Worth a try.

Is the World Noisier?

An insomniac himself, Dr. Pigeon is not soothed by his soundscapes because he knows them by heart and will fret over dissonances only he can perceive. “A particular wave on the Irish Coast that crashes too loudly, or a bird that sings in the wrong place,” he said.

“I have a brain that can’t stop working,” he added sadly. “I haven’t found a way to stop its chatter.”

Is the world noisier? New York City certainly is. In 2016, there were 420,000 complaints to 311, the city’s hotline for nonemergency services, more than twice as many as there were in 2011. An analysis of that noise data by The New York Times revealed that bad behavior — loud music and parties — made up the majority of the complaints, followed by banging and pounding sounds.

Alan Fierstein, an acoustic consultant and noise-abatement expert who has been measuring New York City’s clamor for over four decades, said that the city is empirically noisier because there’s just more of everything. More construction, more cars, more people and, most important, more attitude.

“One man’s castle is usually above another man’s castle,” Mr. Fierstein said. “You have this huge amount of real-estate appreciation, and people are paying a lot of money and as a result they feel like they can do what they want.” 

ith its media rooms and central air-conditioning, and apartment combinations that put his fancy new kitchen over your son’s bedroom,” will not produce any undue noises.

Mr. Fierstein can design noise programs that are perfectly tuned to block the pure tones, as he put it, of outside irritants, like bus noises or building mechanicals, that can be played on any speaker system. (He described a pure tone as any sound that has a specific and constant musical pitch, and then demonstrated by making a high beeping noise into the phone.)

“The way to block a noise is not to be as loud or louder” than the offending sound, he said. “You also have to produce sound that’s on the same frequency. One of the things that makes noise so unreasonable is the lack of control. You can’t stand your neighbor’s loud music even if it’s your favorite artist. One benefit of masking noise is that you can call it your own.”

Recently Mr. Fierstein was called in to mediate a dispute between two neighbors, one of whom was so irked by the sound of the other’s air-conditioner that he positioned eight white-noise machines throughout his studio apartment, the noise of which then annoyed the air-conditioner man.

It was the noise-machine man who sent for Mr. Fierstein. His report noted that the air-conditioner, a window unit, was emitting “audible pure tones,” he said, and may have been improperly mounted, shaking the framing of the building. That would be a win for noise-machine man, though the building’s management has yet to weigh in.

Mr. Suarez, the technician whose recipe for a roughed-up box fan appeared on Reddit, suggested that the increased racket we hear is more often living in our heads. The noises we use to “quiet” them are a kind of placebo, he said. Mr. Suarez noted the constant commotions of the news cycle and social media, and made the point that we don’t do enough physical activities during the day to dissipate our energies.

“Even if you turn off the pings on your phone and turn away from your devices,” he said, speaking from his van as he drove to a job, “you’re still thinking, ‘What’s happening with Facebook? With Congress?’ There is so much going on, and so little resolution. When was the last time you heard the end of a story?”