The fourth Volume is lighter on the early landmarks, though there are some gems here, including one of Halim elk Dabh's prescient 1944 wire recorder experiments, Olivier Messiaen's 1937 Oraison for an ensemble of Ondes Martinots, Gottfireid Michael Koenig's remarkable 1967 Funktion Grau, Steve Reich's Pendulum Music a short 1958 electronic work by Ligeti, a rare appearance from Beatriz Ferreya (1967) and a Broken Music piece by the groundbreaking Milan Knizak. There are also some interesting '70s pieces by Laurie Speigel, Alvin Lucier and Francois Bayle (this with Robert Wyatt and Kevin Ayers). The rest, for the most part, are more recent pieces which stand closer to the industrial noise aesthetic, though carefully selected. Stephen Vitiello (2003), and James Whitehead (Air Attack over Kabul Airfield, 2005) both stand out. Another important collection.