Sometime in the 1960s, the “audio transducer” appeared on the audio market. Bearing a passing resemblance to a hockey puck, the transducer consists of the guts of a loudspeaker: a magnet and a coil of wire. David Tudor began his career as leading pianist of the avant-garde. Beginning in 1968, Tudor composed a series of pieces under the title of Rainforest, culminating in Rainforest IV, developed in conjunction with a workshop in electronic performance that he gave in Chocurua, New Hampshire, in 1973. Due to the physical properties of the crystal, to get most vibration out of a piezo disk speaker, it is necessary to feed it a very high voltage signal, albeit at minuscule current. David Tudor’s Rainforest is one of the most conspicuous compositions to use transducers to resonate materials, but other sound artists have employed similar technology to different musical ends. For Tisch German artist Jens Brand installed speakers inside a circular plastic café table.