Composers have traditionally mixed electronic sounds with instrumental ones to extend the range of timbres and textures available to them and to dramatize the differences between the “human” and the “technological.” Often the sounds of one seem to grow out of the other, causing a confusion of identities which creates intense listening moments for the audience. Varèse does this in Deserts by interweaving recorded material with live instrumental sections. In Boulez‘s Répons, computers transform the live sounds in real time.
I have written two orchestral works, which include pure (sine) wave sweeps (glissandi) against which players sustain long tones creating audible beats. In Crossings (1982-84) a single pure wave sweeps up through the entire range of the orchestra at a constant rate of speed. The players sound tones across the rising wave, producing beating patterns which slow down and speed up as the wave approaches, reaches unison with and passes beyond the fixed instrumental pitches. In Ovals (2001) two waves “draw” an oval shape over the course of 18 minutes. The strings, divided into two sections, outline a similar oval at a 3-minute time lag. In each work the interaction between the electronic and acoustic sounds is physical; it causes the beating. The rate of speed of the sweeps determines the tempo, as well as the rhythms of the works. The shapes of the sweeps are structural; they outline the forms.