“The mystery noise might be part of a worldwide phenomenon referred to as The Hum. According to a 2002 article in the Journal of Scientific Exploration, the Hum is an untraceable sound heard around the world by 2 percent to 10 percent of the population. The report rules out the hearing disorder tinnitus, and suggests that some people have the capability to interpret radio transmissions at certain wavelengths as sound. The report also notes that the only reliable relief from The Hum is a masking noise, such as the sound from an electric fan.”
“A website called The World Hum Map collects reports from people who hear the noise. The closest entries to Thurston County were posted in March 2014 by a Tenino resident and in January 2013 by a Yelm resident. Both reports describe the sound as similar to a diesel train engine,” quoting Andy Hobbs in The Olympian.
Click here for
“The World Hum Map and Database”
“Hum Database Map and Low Frequency Noise Research”