As large-scale data center proposals pop up around the St. Louis region, one of the biggest concerns among residents is noise pollution.
Across the country, people living near the largest data centers have complained about the sounds they emit, even taking their arguments to the courts with multiple lawsuits.
Here's the sound of the Space X Colossus 1 facility in Memphis, recorded by Richard Banks at WBHM in Birmingham, Alabama, for a series on data centers.
To understand how data center noise is different from other sounds, St. Louis Public Radio's Kate Grumke sat down with St. Louis University professor Kasey Fowler-Finn, who studies sound and especially low-frequency noise. Here are three takeaways from their conversation.
1. Data center noise can stand out from other city noise
Data center noise is fundamentally different from other noises humans produce in cities, Fowler-Finn explained.
"A lot of the sound that is produced by traffic, by normal industrial installations is going to be mid- to high frequency, and it's also going to be spread out over a bunch of different frequencies," she said. "So that's going to sound kind of broadband, like maybe hissing, there may be clunks in there, but it's going to be more spread out across multiple frequencies."
Noise from large data centers, on the other hand, is concentrated in low frequencies, Fowler-Finn said. That makes it sound like a hum that stands out.
Fowler-Finn compares regular city noise to the rumble of a train passing by and data center noise to a child's scream.
"You can still hear that scream above the train because all of the sound is concentrated into a single frequency," Fowler-Finn said. "And that's why these data center hums tend to be so piercing and so evident is because they're concentrated in single frequencies and they really stand out from background noise no matter how loud or what frequency that background noise is in."
Fowler-Finn also said the low frequency noise is harder to dampen with structures or plants. That means it can travel farther.
"For traffic sound, you may not be able to hear it past, like, 300 feet," Fowler-Finn said. "But a low-frequency hum from a data center might travel 800 feet or further. We know that the greatest area of impact from these large data centers is 3,000 feet, which is about half a mile."
2. Sound pollution can impact health
Excessive noise can hurt human health, according to the World Health Organization and multiple studies.
"There's a pretty big body of literature on how noise pollution impacts human health, and this applies to both low frequencies and high frequencies," Fowler-Finn said.
Noise is a form of environmental pollution, Fowler-Finn said, and like other pollutants it can negatively affect both humans and other living beings. Negative health impacts can include sleep disruption, hypertension and hearing and cognitive impairment, the WHO reports.
And the sound from data centers can have far-reaching impacts on human health, Fowler-Finn said.
"They increase cortisol. They increase cardiovascular risk. They decrease cognitive functioning, especially in children. In a hospital setting, they can delay healing and recovery," she said.
Fowler-Finn is especially concerned about those health impacts in the area around a proposed project in Midtown, known as the Armory Data Center, and she has brought those concerns to public hearings.
She points to St. Louis University dorms and the new Children's Hospital wing that are within a half-mile of the site.
"I suspect that anyone within that radius is going to be having a much harder time sleeping, concentrating, their health is going to be impacted by a data center in that site," Fowler-Finn said.
The developer behind the Armory project said they are taking the question of low-frequency sound seriously and contend that sound is not only a problem with data centers.
"What's different about the Armory Innovation District is that our permit imposes tougher restrictions on this site, beyond the city's general noise rules which regulate other commercial uses," said David Daneshforooz, CEO and co-founder of TerraWatt, the company developing the project.
3. Fowler-Finn wants cities to do more to regulate data center sound
St. Louis recently passed new regulations for data centers that include multiple measures targeting noise pollution. They require annual third-party reports on noise emissions, acoustically treated enclosures around noisy equipment and 600-feet setbacks for major data centers from schools, residential facilities or parks.
But Fowler-Finn said the setbacks are "woefully insufficient" because the most severe impacts fall within 3,000 feet. She said other measures in the new policy should be tightened to better monitor low-frequency sound.
The new policies also don't apply to the Midtown data center project because it was approved before they were in place. The data center is instead regulated by its conditional use permit, which has different policies on sound.
"Once in operation, independent monitoring will measure the sound produced, including low-frequency, identify any issues so that we can address them," Daneshforooz said in the statement. "These are enforceable requirements of the project's approval, not voluntary promises. Our responsibility is to meet those requirements and be a good neighbor."
For any city considering allowing a large data center to build in its midst, Fowler-Finn has written a policy framework on sound regulations. She also wants data center companies to do more on their end.
"If developers have multiple billions of dollars to produce these installations, instead of fighting to put these in where people live and work, they should be working on technology that makes these friendlier to the environment," Fowler-Finn said.
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