A MYSTERY two tone hum has turned Mariana Robinson's life upside down since it appeared six weeks ago.

Noise experts from electricity company Western Power Distribution have been left baffled by the low frequency hum and Welsh Water turned off the pumps into a water tank near her home above Llandogo in the Wye Valley but the hum has persisted.

She is hoping that a reward of £100 will bring somebody who can trace the source of the noise which she says is affecting her health.

Mariana, who owns a gallery in St Briavels, said: "On the night of March 31 I was awoken by a low-frequency hum like a motor, generator, pump or possibly a turbine.

"It has continued unabated since, 24 hours a day, and it gives me tremendous headaches and prevents me from sleeping.

"I cannot hear the noise in my gallery in St Briavels and neighbours can hear in and around my house but not down the hillside in their own homes.

"The environmental health people from Monmouthshire Council have been good but they have not been able to find where it is coming from.

"It has been suggested that it could be coming from farther away and it is vibrating through the bedrock.

"I'm willing to offer £100 to anyone, such as an acoustics expert or geologist, who can can trace the whereabouts of this noise and switch it off so I can get some peace."