Herald reporters Emma Elder, Meiling DellaGrotte and Emily Smith investigate the mystery hum
Do you remember the mysterious story about a low-pitched humming noise which left scientists baffled and caused residents to cover their ears?
Last summer
The Herald reported on the
strange phenomenon creating a stir across the Plymouth area.
We thought the nuisance noise had disappeared, but now it seems to be back and more disruptive than ever. People have reported hearing the noise at night in Keyham, Devonport, West Park and St Budeaux.
Pat Finnie, who lives in Normandy Way, St Budeaux, says she and her husband have noticed the "melodic, droning" sound returning.
"I have heard it several times over the last few weeks and then on Monday and Tuesday this week," Mrs Finnie said.
"You begin to wonder whether it's you, your ears, but my husband said he could hear it too, and he doesn't usually notice it.
"My neighbours have been aware of it too, several people say they have heard the same thing."It's a very low, almost melodic sort of sound.
"You wake up and thought it was something in the house. You can't say it's loud, but it's a nuisance.
"We don't hear it in the daytime, only at night."
The strange droning noise - which only two per cent of people can hear - was first reported in the 1970s.
People as far apart as New Mexico and Somerset have been complaining about the 'mystery hum' ever since, with some saying it has driven them mad.
Bizarrely, the irritating noise is usually heard in rural areas - and only ever indoors and is also apparently louder at night.
It has been blamed on everything from electricity pylons to sonar waves.
But boffins are still scratching their heads 40 years on.
Yesterday we asked users of our Facebook page for their theories.
Sharon Childs said she thinks it is caused by tinnitus, Dylan Finley reckons it could be aliens, while Jordan Hewitt said: "It's the magnetic fields around the earth and sounds bouncing back. Sometimes a hum, sometimes loud like trumpets. A worldwide phenomenon."
Tina Wills has a theory that it is coming from the dockyard, and Richard Williams thinks it is "election babble".
Daisy Rose said: "I hear it mostly at night when it's quiet and I'm watching TV. I have to keep pausing it because it's so annoying. It does sound electrical in a way. Strange!"
A spokesman for the Ministry of Defence said: "No complaints have been received." If this noise is really being heard across Plymouthit is unlikely to originate from the Naval Base. "We have constant generators here but they are not loud enough to be heard by anyone but the nearest residents."
According to a recent study in Geophysical Research Letters, the hum comes from so-called microseismic activity, largely due to ocean waves.
What could be causing the hum?Magnetic fields around the earth
Ocean waves
Electricity pylons
Tinnitus
The dockyard
Election babble
Aliens
Gremlins
Cannibal rats
Man-eating sharks
Twitter
I never really thought anything about it until I asked other people if they could hear it and only two of the ten or twelve people I asked could.
The fact that those two people could hear it only made this more mysterious to me.
To me the idea that it is an electro-magnetic resonance effect in the atmosphere makes the most sense.