Iannis Xenakis, with his penchant for complex textures of sliding strings and raucous brass, seems an unlikely composer to write for the harpsichord. As one of the most delicate of instruments, the harpsichord is rooted to historical eras that Xenakis has tried to avoid, such as the Baroque. But, if you take a vivacious, red-haired performer with an attraction to new music and a compelling desire to create a new repertoire for her instrument, construct a more powerful instrument and couple it with the judicious use of amplification -- well, then you have a combination that proved irresistible.
As it turns out, Polish harpsichordist Elisabeth Chojnacka would become one of Xenakis' most dedicated allies, performing his music around the world to great acclaim. Khoaï, composed in 1976, was the first of five works he wrote for her and the first of the two solo pieces (Naama dates from 1984). This music has nothing to do with the traditional repertoire. What attracted Xenakis to the instrument, particularly in its more muscular, amplified form, was its ability to articulate layers of precise rhythmic patterns, and to create powerful percussive sounds (unless you are sitting next to the harpsichord, this really is music for the modern, amplified age). Xenakis also discovered that the different registral attributes of the instrument enabled him to exploit a wide range of timbral shifts. The elaborate timbral changes and rapid leaps between the two keyboards make Khoaï a strangely physical piece, and certainly Chojnacka has made much of the choreography.
The music is episodic, alternating between passages of ever-shifting rhythmic patterns and dense polyphony in which melodic tendrils, often proceeding at different tempos, intertwine to create proliferating textures that Xenakis terms "arborescences." The rhythmic flux creates an improvisatory quality, though this is music closer to the avant-garde jazz of Cecil Taylor than to anything more traditional. The densely chromatic harmonies are most often mere by-products of contrapuntal concerns, but there are tonal reference points along the way. Certain recurrent pitches are emphasized through repetition and octave doubling. The title means "offerings or libations to the gods of the inferno." Khoaï, in a strange way, takes the genteel nature of the harpsichord and casts it into the fiery realm of the inferno as conveyed by one of modern music's most fiercely uncompromising but utterly imaginative composers.