The specified pitches are made to generate their own accompanying frequencies, generally inharmonic with respect to the pitches themselves, as a result of FM or AM procedures. Each interval, or, in fact, each pitch-pair (or if you don't want to limit yourself to the chromatic scale, each pair of arbitrarily decided upon frequencies) can generate several possible spectra, but the similarity in sound quality between kinds of spectra quickly reduces to a limited number of readily manageable families of chord-types. These chords are the basis for a variety of musically interesting relationships, and this work represents but one of many possible developments of these kinds of sounds. The clarinetist in this recording is Philip Rehfeldt.