Residents in De Beauvoir Town have been left sleepless as a mystery high-pitched noise continues day and night.
Council workers and electricians are bemused by the buzzing sound on a section of Northchurch Road.
Among the possible causes being looked into are an electronic pest scarer, a faulty alarm system or damaged overhead wires.
But investigations by British Telecom and the council’s Noise Pollution Department have turned up no answers.
Hilary Scarlett, who lives on Northchurch Road, said: “It’s a continuous high-pitched noise in a section of Northurch, Culford and Lawford Roads. It is present 24 hours a day and it’s driving some of us mad.
“I spoke to the council this morning and they are still as mystified as we all are. They have been here at all times of day and night and have tried to gain access to as many properties as possible to rule them out.
“They have even been into an empty property and into its garden.”
Paul Bolding, chairman of the De Beauvoir residents’ association, said: “I didn’t realise that people had got up quite such a campaign about it until I spoke to Hilary. People have been calling the council repeatedly.
“The noise goes on through the day and night, although during the day I suppose it’s masked by traffic and other sounds. It’s a real mystery.”
Hackney Council declined to comment. Anyone with information should call the council’s Noise Pollution Department on 020 8356 4455.