Close defined his Earth Harp as:
A string instrument that uses its environment to create the instrument. So a typical scenario for the Earth Harp is that the chamber or the resonator of the instrument would rest on the stage and mount on the stage and then the strings would run out over the audience and attach into the balcony of the theatre or the architecture itself. So it actually uses the architecture to create the instrument.
With said characteristics, the harp can reach 10 or 3000 metres, a variable length that affects the sound of its strings, which at the same time can vary between 16 and 22, depending on the place where it is mounted.