In 2002, the city contracted with an acoustics consulting firm to pinpoint the problem. The contractor found that two industrial plants were indeed generating low-frequency tones and those plants are now working to correct the problem. But few believe that is the entire story. "You can be sitting right next to people hearing it, and I can't pick it up with my instruments," says Jim Cowan, senior consultant for Acentech. Sounds from magnetic fields and geomagnetic activity, such as power lines and solar storms, are another possible explanation.
People in New Mexico and several European countries also have reported hearing a local hum.
The people in Kokomo who complain range from those who likely are legitimately suffering to "some folks who are fairly radical in their beliefs," says corporation counsel Kenneth Ferries. "We had a guy who insisted the Navy is drilling a tunnel from the East Coast to the West Coast and said, 'Don't worry about the hum because they're just passing through.' What do you do about that?"