Driven to distraction by the sound of ‘screaming’ children in the garden next door, Michael Mitchell and his wife Kathryn hoped technology was the answer to their problem.

The couple installed a device outside their home which emits a high-pitched noise that is uncomfortable to listen to and was set to be heard only by young people.

The anti-loitering equipment had the desired effect and sent the four children, all aged under ten, scampering inside whenever it was switched on.

Michael Mitchell and his wife Kathryn installed a device outside their home which emits a high-pitched noise that is uncomfortable to listen to and was set to be heard only by young people

But their peace and quiet is now under threat after the neighbour complained to the council and the couple were warned they faced legal action for ‘creating a detrimental effect on the quality of life of others’.

Mr and Mrs Mitchell – who have been taken to court for harassment but acquitted during the long-running dispute with their neighbour - have vowed to continue using the device if necessary, despite the threat of a £2,500 fine.

They even admitted adjusting the device recently to emit a lower pitch to irritate adults, claiming their neighbour Beth Chappell, 36, put on loud music late one night.

‘I was really annoyed to get this letter [from the council]. It switched things around from us being victims and is making out that we are the perpetrators. It is horrible,’ said Mr Mitchell, 66, who has three children and two grandchildren.

‘I don’t believe the device is anti-social. It is the only recourse we have to deal with a noise nuisance because nobody wants to take any notice of us.’

The anti-loitering equipment had the desired effect and sent the four children, all aged under ten, scampering inside whenever it was switched on

The couple, who have been together for four years and married two years, bought the £130 Ultrasonic Teen Deterrent device in August, claiming they had suffered two years of ‘unbearable’ noise.

They attached the eight-inch high black box on the exterior side wall of their three-bedroom terraced house in Ipswich and ran wiring inside so that they could control it from their rear bedroom.

It was switched on up to three times a day, usually for ‘two or three minutes’ at a time – although sometimes up to ten.

They claimed the children had been ‘encourage’ at times to make a racket.

But they learned they were under investigation on September 29 after receiving a letter from Ipswich Borough Council’s environmental health department.

This was followed up by a letter this week from council officer David Newman who said the local authority was ‘satisfied that your conduct is having a detrimental effect on the quality of life of others in the locality’.

He warned they could be issued with a Community Protection Notice under the Anti-social Behaviour Crime and Policing Act 2014 if they used the device again.

If they breached the notice they faced being taken to court where they could be fined £2,500 as well as having to pay costs.

But they admitted using it on October 10 when they were bothered by the late-night music, after which they say Mrs Chappell’s partner offered a ‘truce’.

Mr Mitchell, a retired science teacher, said: ‘I don’t mind the noise of children playing happily.

‘It is perfectly okay to hear them squeaking and laughing – but their screaming was on another level.’

His wife added: ‘We have never wanted to stop the children playing. We just want to stop them screaming too loudly.

‘I got so bad in the summer that we were unable to sit outside and have a meal or enjoy a glass of wine.

‘We also had to shut our windows and doors. We were constantly on edge waiting for the noise to happen.’

The couple said they were visited by police seven times for allegedly shouting at the children and swearing at Mrs Chappell before they were arrested for harassment last year.

They were fingerprinted, DNA tested and held in separate cells for six hours before they were charged. But they were acquitted by Ipswich magistrates in July last year.

Mrs Mitchell, who suffers Type One diabetes, said the stress of the arrest led to her giving up her job as an office administrator.

The anti-loitering device was bought from a security company which said on its website it was ‘100 per cent legal to use’ and met all EU regulations.

Similar alarms have been used in the past at shopping precincts to disperse gangs of unruly youths but allow adult shoppers whose hearing isn’t as acute to carry on as normal.

The noise they emit, at around 17.5 kilohertz, has been likened to scratching nails down a blackboard. Human conversations range from eight to 16 kilohertz.

Pets aren’t affected by the noise.

Mrs Chappell declined to comment when approached at her home.

But a friend said: ‘Her kids don’t make any more noise than normal. She certainly doesn’t encourage them to scream.

‘It is out of order for Mr and Mrs Mitchell to have this high-pitched alarm on their home. It upsets the children. They’ve been in tears.

‘The Mitchells have had it switched on for long period so you cannot get away from it. Sometimes they’ve had it switched on for hours at a time.’