Otomo Yoshihide is one of the most creative sound artists nowadays, experimenting with both medium and form. For much of the 1990s his main project was Ground Zero, a large group founded with an everchanging lineup. Towards the end of that group's life, Otomo formed two electronic free improvisation groups: Filament with Sachiko M, and I. S. O., with Sachiko M and Yoshimitsu Ichiraku. These groups abandoned the frenetic postmodern pastiche of Ground Zero, and emphasized small gestures and low volume. The music contained no samples, being made of sine waves and electronic clicks and hums. Yoshihide largely stopped using records as a sound source, instead manipulating the turntable itself with a wide variety of objects and contact microphones.