Dr. Peter Rabinowitz, a member of the American College of Occupational & Environmental Medicine's Sensory Perception Committee, said he is unaware of any datacenter-specific research on noise. While OSHA sets standards for action, low-frequency noise coming off fans and air handling systems can affect concentration and produce fatigue, he said.

"In general, I think people like to work in a fairly quiet workplace," said Rabinowtiz.

There is no single agreed-upon decibel level standard for protecting workers who must deal with the constant din of datacenter noise. But if workplace noise reaches 85 dB, it triggers some steps under law in the United States. By contrast, Europe's workplace protections begin at the 80 dB level.

The question is: Who's measuring? There is an absence of studies on noise in the datacenter, said Mark Stephenson, a senior research audiologist and coordinator National Institute of Occupational Safety & Health (NOISH) hearing research. NOISH is part of the U.S. Centers for Disease Control and Prevention.

"I'm not aware of studies that have demonstrated that working in a datacenter exposes you to hazardous noise," Stephenson said. "However, there certainly could be something out there.

"The trend toward larger and larger facilities would have a slow incremental increase in the noise level, so it's possible that something like [crossing the legal threshhold for action] would creep up," said Stephenson.

If the noise level reaches 85 dB over an eight-hour day, that should trigger some monitoring under Occupational Health and Safety Administration regulations. If noise levels hit 90 dB, then companies are required to take steps to protect workers' hearing.

Whether noise is an issue for an IT manager depends on the type of datacenter. In some future scenarios -- think of it as the ultimate lights-out datacenter -- the facility might be, in total, a computer: a highly interconnected operation that's remotely managed, with self-healing, self configuring systems that's rarely entered by personnel. Noise won't matter as much.

But most datacenter operations are far from the lights-out ideal and are run by people like Nick Martin, the IT manager at Taco Metals, a North Miami Beach, Fla.-based maker of marine products. Martin has been in IT since the 1970s and said noise reduction has always been important to him. He likes quiet. He especially likes to talk on the telephone with a vendor when he's working on some equipment, something that was impossible in his datacenter.

Martin replaced his ceiling tiles with sound deadening acoustic tiles and installed the same tiles on some of the datacenter's walls. "It really knocked the sound down quite a bit," he said.

Using a headset, Martin said it now is quiet enough to "go from my office to the computer room working with the Microsoft tech flawlessly, so there is no interruption in tech support." That matters a lot, he said, because it helps avoid downtime.