Portola Valley: Thing(s) that go hum in the night Portola Valley: Thing(s) that go hum in the night (December 21, 2005)

** Town residents report mysterious hum that keeps them awake.

By David Boyce

Almanac Staff Writer

A mysterious low-frequency hum that has been haunting the quiet nights of at least four Portola Valley residents is nothing if not persistent.

First heard in late August, it can change with the weather, and the pitch sometimes varies. But so far, no one knows what's causing it.

"It's winter and I have to sleep with the fan on all the time," said Brookside Drive resident Annaloy Nickum at the December 14 Town Council meeting.

"It kind of creeps in," said Stephen Dunne, who lives on Canyon Drive and who said he is sometimes deprived of all but two or three hours of sleep. "Ear plugs don't work," he said.

Councilman Richard Merk reported that he has heard the noise, but that it doesn't keep him up at night.

Leslie Lambert, the town's planning manager, is the point person on the staff trying to resolve the problem. "It has been frustrating. I want to help, but I'm at a loss at this point," she said.

The affected residents live within a half-mile area south and east of The Sequoias retirement community, home to about 300 people. If the noise's source is there, the management will cooperate in finding a solution, Ms. Lambert said.

It could be a pool pump or a generator or a transformer, she said. She has also talked with representatives from the water service and the sanitary district, but so far to no avail.

In a town many residents like to think of as rural, the residents hearing the noise may be "canaries in a coal mine" -- providing an early warning of a hum from an encroaching industrial world, said Ms. Nickum.

Whatever the source of the hum, it's no ordinary matter, said Councilman Ted Driscoll. "I don't think a layman is equipped to handle the problem," he said. "This is a problem for scientific investigation."

Professional help is on the way. The council discussed and then agreed with Ms. Lambert's recommendation to hire an acoustical engineer to locate the source of the noise, but at a cost of no more than $2,000.
A night visitor

An Almanac reporter, along with Mr. Driscoll and Councilman Ed Davis, visited Mr. Dunne's home at about 11 p.m. December 14 after the council meeting broke up.

After a minute or two of silent standing in a dark bedroom, the reporter heard a very, very soft deep hum with the rhythm of a clothes dryer.

"You're trying to get to sleep and it goes right through you," said Mr. Dunne. "It goes right to your bones."

"My great fear is that this is not caused by one source," said Mr. Driscoll, who has a doctorate in Earth sciences and satellite imagery and who was inconclusive about whether he heard the sound that night.

Mr. Davis, who has a doctorate in electrical engineering, said in an interview afterward that he heard a very low frequency growling "every once in a while."

"It's clearly a low-decibel type of sound, if it's there, and I suspect it is," he said.

If it does have more than one source, that "greatly increases the mystery," he added. "I love a mystery and this one is really one of the better ones. I hope that science comes to the rescue."

E-mail a friend a link to this story.