Sirens normally sound to alert people to an imminent danger. But a group of musicians in southern France have transformed public warning sirens into instruments. They produce a mysterious and captivating music, attracting the attention and amazement of those who hear them.

People strolling around in French City of Rennes lift their heads up when they hear the unusual sound. The music comes from some sirens placed on the Opera building. Alarm devices normally situated on tower blocks and industrial sites to alert in case of fire or other danger are now emitting a much more attractive melody.

Some are surprised, some are puzzled by this open air concert. In a disused industrial hangar in Champlauson, Gard, Franz Clochard, a musician and circus performer, has spent the last ten years giving a new lease of life to these objects.

Clochard's company called "Mecanique Vivante" (Living mechanics) has transformed alarm devices collected form all over the world in to playable instruments. The sound is created by an instrument he has created called the "Sirenium", an electronic device which he plays like a double bass.

He explains how the notes correspond to a piano keyboard, and how the tone is obtained. Clochard, whose name coincidentally means bell ringer, explains that a siren swallows air and spits it out therefore creating frequencies in the air outside. He says that unlike sound diffusion systems like loud speakers, the sound is not electrically enhanced or modified, thus it is really acoustic music.

Ideal for playing outdoors, normally the sirens are locked in this room for rehearsals. Two alto, a tenor and a bass instruments they produce a powerful chant. Franz Clochard says that in France public safety laws means that there must be sirens to protect public safety near industrial sites, which are tested on the first Wednesday of the month. Thus many French people are accustomed to hearing these sirens, but never before have they been so melodic. The sounds created by the sirens are capable of being heard 5 kilometers (3 miles) away.

Ann Baetz, who finds venues for the band, says it is not easy to bring the Sirens song to French towns, it is easier in other parts of Europe where she says people are more interested in new and different experiences.

The band, which has eight members including a Scottish songwriter, plans to expand the number of sirens. In 2007 Mecanique vivante played in Pont Du Gard, the roman aqueduct near Arles, at the Festival de la Loire in Orleans, a Santa Maria de la Feira in Portugal, at the Nuits blanches in Madrid, and last 16 September, 2007 in Newcastle in the north East of England for the arrival of the transatlantic liner Queen Elizabeth II.