Karlheinz Stockhausen’s ‘Helikopter-Quartett’ – just released on CD – “is just as it sounds. It’s a string quartet written to be performed with each of the four players hovering above the concert hall in a separate helicopter. A ‘click track’ helps keep them together, and their individual parts, plus the ambient noise of the helicopters, is beamed down to the concert hall, where it is reassembled by sound engineers. In an ideal performance, the actual whir of the helicopters above the concert hall would be just barely audible, blending into the electronically received individual parts. It has not had many performances, ideal or otherwise.” – Washington Post