Odd noise has some Olympia residents humming

Some Olympia residents are baffled by a mysterious humming sound that not everyone can hear.

Dale Phillips said he hears a low-frequency drone that occurs like clockwork, typically between 10:30 p.m. and 3 a.m., although the sound surfaces at other hours with varying intensity.

“It has become a real bothersome issue,” said Phillips, who recently purchased a home near Sunrise Park in west Olympia. “At this point, I feel like I can’t live here.”

Phillips has canvassed his neighborhood to find the sound’s source. He once contacted Tacoma Rail to see if the hum came from trains that idled on the tracks. Last week, he approached a man who was pressure-washing sidewalks at night. But for now, he can only speculate.

“Everybody might not hear it,” Phillips said, “but it’s there.”

Phillips voiced his frustrations about the noise in a recent letter to The Olympian that attracted a handful of responses, but no concrete answers. City staff has been unable to locate hum-related complaints, said spokeswoman Cathie Butler. Possible sources for the hum are HVAC units on buildings, power stations, underground or overhead wires, neighbors with heat pumps, ships at the port, or even failing traffic signals, Butler said.

Dave Sederberg contacted Phillips about the hum, which he encountered about 10 years ago while living on Cushing Street in west Olympia.

The mystery noise sounded like rumbling trains and would wake Sederberg at night. He finally got into his car and tracked down a possible source: Parking lot sweepers that went to work after the stores closed near Capital Mall.

“It was irritating and loud,” said Sederberg, a sound engineer who owns Pacific Stage in Olympia. “Sound waves will carry a long way in the right conditions.”

Parking lots are usually swept at night because they’re full of cars during the day, noted Rich Hamilton, co-owner of Best Parking Lot Cleaning. The company cleans parking lots in the Target Place Plaza area, and Hamilton acknowledges that sweepers can be noisy.

“There’s no perfect time to do it,” he said.

Scott Schoengarth also hears a mysterious hum — but he lives in northeast Olympia near Mission Creek Park. The recent letter by Phillips confirmed that he was not alone.

“My wife doesn’t hear it, so she thinks I’m crazy,” said Schoengarth, who hears the hum in the middle of the night or early in the morning — and has tried without success to pinpoint the source. “Sometimes it’s hard to ignore.”

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.

In 2012, residents of West Seattle reported a strange nighttime hum. Possible sources included everything from a ship-unloading operation to the mating call of the midshipman fish, according to media reports.

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.

Andy Hobbs: 360-704-6869