Researchers have found no trends related to gender or age for the “hearers.”

Dr. Darius Kohan, the director of otology and neurotology at Lenox Hill Hospital and Manhattan Eye, Ear and Throat Hospital, said that the low-frequency hum was unlikely to cause long-term hearing damage but that it could be as debilitating as tinnitus, a persistent ringing in the ears.

Scott Barton, an assistant professor of music at Worcester Polytechnic Institute in Massachusetts, said in a phone interview that infrasound, which is below 20 hertz, can create a sense of unease because it is unintelligible to human hearing but still detectable. While it is possible to be accustomed to certain noises (the hum of an air-conditioner, for example), this low-frequency noise is challenging because it has been so inconsistent, he said.

Seeking intervention by government regulators for the hum is difficult because regulations typically address decibel levels that can lead to hearing loss or damage, not those that can affect quality of life, Rebecca Smith, a sound engineer and doctoral student at the University of Michigan in Ann Arbor, who researches urban noise, wrote in an email.

“Think about the sound of a dog barking,” she said. “It doesn’t need to be loud enough to physically damage you to be really annoying and distracting.”

The University of Windsor report said the hum’s likely source was blast furnace operations on Zug Island on the Detroit River, which is densely packed with manufacturing. Activists complained that United States Steel, which operates the furnaces, has been uncooperative and secretive. A company spokeswoman did not respond to requests for comment.

A principal investigator on the study, Professor Colin Novak, told CBC News in 2014 that researchers needed more time and cooperation from the American authorities to pinpoint the source. “It’s like chasing a ghost,” he said.

Hums similar to Windsor’s have been reported in at least a dozen communities worldwide, including in Australia, England and Scotland, the study said. In the United States, high-profile hums have been reported in Taos, N.M., and Kokomo, Ind.