The plot is beginning to thicken over the fabled 'Llanidloes Hum.'

No longer can it be traced to one source, as discovered this week when a Middletown reader contacted County Times to tell of his experiences.

Tony O'Leary, who read the story of Peter Danks' experiences of the hum, contacted us to say he too is suffering at the hands of this mysterious force: "It has been happening now for around two years," said Mr O'Leary, "There is a sort of quiet buzzing noise we can hear which comes and goes. I've heard it, and the fact that my kids and wife have also heard it means I'm not imagining it!"

The incident in Llwyn Y Gog, Staylittle, could be traced back to the nearby Carno windfarm extension. The dates when Mr Danks began hearing the low-frequency noise coincide exactly with when the 12 new turbines were powered up. But windfarms can not be blamed for the Middletown hum, as there are none within a 20+ mile radius.

"It's really annoying," said Mr O'Leary; "It isn't obvious at first but once you notice it it starts to bug you."

Another reader got in touch from nearer Llandinam to say she too could hear the strange hum. The woman, who wished to remain anonymous, said: "We live a bit away from any windfarms, including the Llandinam site, so it is unlikely that they are to blame. It is strange though.

My doctor has diagnosed me as suffering from Labyrinthitis, but I'm sure it is something else."

The famous Bristol Hum of the 1970's draws parallels with what the three readers are experiencing. No firm answers were ever reached as to what has caused the humming, and despite research being carried out by celebrated University academics, we are no closer to finding an answer.

Possible reasons include buzzing caused by faulty electrical wires through to internal hearing and balance problems. Whatever it is, it is causing a lot of discomfort and annoyance for an increasing number of people.