Of Radiant Streams (1985), for four percussionists and tape, is the first of my pieces that was directly influenced by McTavish’s work.  I was interested in exploring the physical, acoustic possibilities of percussion instruments, especially through rhythm—rhythm as patterns in space and time, as cyclic repetition, as a pattern with a steady beat.  I also wanted to work with a perceptual phenomenon I had read about called “streaming”.

A repetitive cycle of tones spread out over a certain frequency range may be temporally coherent, or integrated, at a particular tempo.  It is possible to gradually increase the tempo until certain tones group together into separate streams on the basis of frequency. . . The faster the tempo, the greater the degree of breakdown or decomposition into narrower streams until ultimately every given frequency might be beating along in its own stream [4].

The title Of Radiant Streams is a reference to streaming—a perceptual attribute of the auditory system in which the fission of individual elements at high speed creates several streams.  The word stream is also related etymologically to rhythm; both are rooted in the Greek rhein, meaning “to flow”.

Another essential element of my piece is room acoustics—I mapped out a general range of resonant frequencies for performance spaces and planned to have the whole room vibrating sympathetically with intense sound pressure by the end of the piece.  I began by establishing a frequency range from the extreme registers of the highest and lowest instruments.  The highest instrument was the glockenspiel (4, 186 Hz.) played with brass mallets to maximize the high frequency of the sound.  The lowest was the bass drum (50 Hz.).  I then expanded the frequency range by taping and then playing back the original sounds at up to four times the original speed.  The taped part in Of Radiant Streams consists of a steady stream of multitracked, acoustic sound with continuous internal timbral modulations.  The form of the piece is based on a Fibonacci spiral (Fig.2)—the total duration is 21 min. and the structural points of each recurring cycle occur at 1,2,3,5,8 and 13 mins.

Fig.2.  The composer has marked the Fibonacci spiral, which forms the basis of Of Radiant Streams (1985), with indications for the recurring cycles within the composition [9]