Almost by accident, the German musician and sculptor Armin Küpper came across a set of huge gas pipes. Yelling into them, he discovered the beauty of natural delay and reverb. So, he returned with his sax, and later with a guitar – and a new genre of call and response was born. The sounds he creates, and the accompaniment of the perfect-pitch echo, is quite extraordinary. Küpper  has posted a series of YouTube videos of his pipe gigs. Enjoy.