But as well as catching the eye they're also supposed to be pleasing on the ear.

The special foam pieces have been installed to absorb noise in a busy school corridor while pupils sit exams or detention.

A group of 25 pupils with autism, Apserger's syndrome and special educational needs spent five months working on the innovative project, starting with visits to the University of Southampton's Institute of Sound and Vibration Research.

They then worked with Portsmouth artist Jon Adams to sculpt acoustic foams – used to soundproof recording studios – depicting Portsmouth landmarks, such as Fratton Park, the Spinnaker Tower and HMS Victory.

The foam pieces were arranged in two blocks and now hang from the ceiling outside the school hall.

Science teacher Matthew Round said: 'You can hear the difference and we've had people from the Institute of Sound and Vibration Research come to measure the reduction in background noise.

'The change in the children's confidence has been massive. A lot of them couldn't speak in front of people but when doing this they were doing mini presentations to groups of four or five people.'

Mr Round said the pupils gained a lot from working with dyslexic artist Mr Adams.

He said: 'It was one of the most fascinating things to watch.

'I'm a dyslexic myself and Jon has severe autism and Asperger's so it was nice for the pupils to see someone like him do something important with their lives.

'And I think it was worthwhile for Jon because he had his own pre-conceptions from his own childhood on how schools treated pupils with SEN so he could see how much has changed.'

Mr Adams is working with the Tate Modern about the principles of sound absorbing art while the school will do a film about the experience for the government's creative learning programme, Creative Partnerships, which supported the scheme.