AN expert in sound frequency has offered an explanation for a mysterious humming noise which has been plaguing a village.

Dr Chris Barnes, who has written several books on ultrasonic sound, dial-electrics and electronic noise, started to investigate the sound coming from Woodland, near Bishop Auckland, County Durham, after reading about it in The Northern Echo in June.

The story of the Woodland hum – described as having a low mechanical sound to it – took Dr Barnes’ interest as he is also investigating a similar phenomenon in his home town of Bangor, North Wales.

The phenomenon is experienced across the world.

Dr Barnes believes the hum is down to anthropogenic noise – sound created by people or by human activity.

More specifically, he says the network of disused mine shafts which run under Woodland and its surrounding area would be the main culprit of the noise. Sound from the electricity grid would also contribute.

In March, part of the B6282 road, near Woodland, sank into what was believed to be an abandoned mine shaft. Dr Barnes thinks that repairs done to strengthen the road could have altered the frequency and volume of the anthropogenic noise.

Dr Barnes, said: “I have spoken to people involved in the hum and have been able to cast a little bit of light on the matter. I was hoping there would have been some major changes in the infrastructure of the landscape, which would have helped explain it.

“There has been an incident recently where a road has collapsed into one of the mine shafts. If the council has then poured a load of concrete into the hole, this would have caused a sufficient change and altered the way the ground-borne noise is produced.”

Dr Barnes also had an explanation for the fact that some residents of Woodland complain that the hum has kept them awake for many nights, while some say they have never heard it.

“Some people are much more sensitive to sounds than others and we can all hear to different levels,” he said.

“Some can hear to much lower frequencies to others, so it will affect them in different ways.”

Dr Barnes also said that the varying ways houses in Woodland are constructed would lead to some transmitting low frequency noise while some block it out. Double glazing, for example, allows certain frequencies in while blocking higher tones.