Helmut Lachenmann
String instruments are capable of producing a variety of extended technique sounds. These alternative playing techniques have been used extensively since the 20th century. Particularly famous examples of string instrument extended technique can be found in the music of Krzysztof Penderecki (particularly his "Threnody to the Victims of Hiroshima"), Witold Lutosławski, George Crumb, and Helmut Lachenmann.