Monodias e Interludios (1984), for 2 flutes, 2 clarinets, percussion and a low-pitched instrument
"Das, was aus jenem Seminaristenspiel und aus Perrots perlenbehängten Drähten später geworden ist, trägt noch heute den volkstümlich gewordenen Namen Glasperlenspiel."
Monodías e Interludios consists of 6 small compositions. The sound material was obtained through the use of techniques of Frequency Modulation, well known techniques in Electronic Music). The main parameters of this technique are the Carrier Frequency and the Modulating Frequency. They generate 'harmonic' spectrae, i.e. spectrae composed of subsets of the overtone series. Thus, all the tones of this composition are overtones of a fundamental, which if it is not to low, it will be played by the low-pitched instrument.
The fifth movement is an exception. Two clarinets play rather loud a two part invention. They genertate a quiet and mysterious melody of 'difference tones'.
A detailed description of the composition can be found in:
Le timbre, métaphore pour la composition
Christian Bourgois Editeur