When I think back to my own childhood I remember the Sunday walks with my family. In Weinheim, Germany there was a special attraction: From the gliding field telephone lines led to to the nearby town, lines which used at that time still thin copper wires. At the wooden masts of the telephone lines we regularly stopped. The children of us were deeply impressed by the melodies or the low hum, which the wind caused in the singing wires in a mysterious way.