The Hum: A Sound Only Some Can Hear

The Story

For some people, it never stops. They describe a low, pulsing drone, like a diesel engine idling somewhere in the distance. It is usually worst late at night. It can be heard indoors and out, and covering the ears does not help. Yet most of their neighbors hear nothing at all.

Reports of this 'hum' have come from communities around the world. Those affected describe headaches, nausea, fatigue and sleep loss, as well as frustration at being doubted. According to acoustics engineer James Cowan, who led one U.S. investigation, many say the sound goes away when they leave the area and returns when they come back, which suggests something external.

In Taos, residents could reproduce the sound they heard on a signal generator. The instruments recorded nothing.

The best-known American case is in Taos, New Mexico. After local complaints reached Congress, a week-long study took place in the spring of 1993, run as an open public investigation involving Los Alamos National Laboratory, Sandia National Laboratories, Phillips Air Force Laboratory and the University of New Mexico. According to Cowan's later summary, 161 people reported sensing the hum out of a survey of 8,000 residents.

The researchers monitored sound, seismic activity and electromagnetic fields while affected residents were hearing the hum. Many residents could reproduce the sound they heard on signal-generating equipment, but no matching acoustic signal was detected by any instrument. The only unusual reading was an elevated electromagnetic field reportedly related to local power lines. No source was found.

Other hums have been solved. Starting in 2011, residents of Windsor, Ontario, complained of an intermittent low-frequency noise. Researchers from the University of Windsor and the University of Western Ontario, supported by the Canadian government, concluded that the 'Windsor Hum' existed and was most likely caused by blast-furnace operations on Zug Island, an industrial area on the U.S. side of the Detroit River. In 2020, after U.S. Steel halted its operations there, a researcher told The Canadian Press that the noise had practically vanished.

Explanations for the remaining cases range from industrial machinery and distant traffic to individual differences in hearing. Some researchers, including Cowan, have suggested that some people may be sensitive to stimuli that others are not. Theories that the hum is caused by secret military transmissions have no supporting evidence. For many sufferers, the source remains a mystery.