The source of the highly annoying Kokomo, Indiana hum, that has been making some people sick since 1999, has now been identified. An acoustics consulting firm says two industrial fans are sources of a mysterious sound.
Jim Cowan of Acentech, in Cambridge, Massachusetts, was hired by the town to make a 10-month study of the hum. He finally traced it to low-frequency and infrasonic tones coming from local industries, and narrowed it down to a cooling tower fan on the roof of Kokomo’s DaimlerChrysler Casting Plant and an air compressor fan at Haynes International.
Both companies have agreed to silence their fans. Haynes International has installed a muffler, and DaimlerChrysler is working on the problem.