Enregistrement : Enregistré sur CD ICMA, International Music Conference 1992, PRCD 1300 (avec Morales, Settel, Kimura, Harrison).

The title alludes to the first communication satellite – a vision which John Pierce turned into a milestone of the history of human communication. One should mention that John Pierce, which coined the word "transistor", was at the origin of computer music : the idea occured to him and Max Mathews during a concert of instrumental music, and Pierce sheltered the developments of computer music at Bell Laboratories when he directed the research between 1957 and 1970. He himself contributed to this development with many insights.

The title also refers to a process of repetition often found in music and used in the realization of the piece : sounds have been processed by adding delayed echoes. If the echoes are very close in time, the process yields comb filtering. In the piece, the "echoes" are often transposed in frequency, using programs performing as harmonizers. At the end of the piece, a clarinet motive is reverberated into a series of echoes going into nothingness. Clarinet-like sounds echo harp-like sounds anre vice-versa. Last, the title reminds of the nymph Echo. In the Greel mythology, Echo, initially too talkative and distractive, was deprived of speech : she could only repeat, reverberate, echo. Echo - a symbol of sound reflection - fell in love with Narcissus - only fond of his own refleted image.

Echo was realized at the Laboratoire de Mécanique et d'Acoustique, Marseille, originally on a 8-track tape. The sounds of the piece were derived from three kinds of sound material : clarinet motives, recorded by Michel Portal; celtic harp motives, recorded by Denise Mégevand; and sound synthesized or processed by computer, using the MUSIC V program (adapted to IBM-PC compatible computers by Daniel Arfib). For instance, shortly after the beginning of the piece, clarinet sounds have beenn transformed with MUSIC V : a harp-like echo is produced by sharp resonant filtering; and some motive have been slowed down without pitch transposition, using a Gabor granular technique implemented by Daniel Arfib. Ascending harmonic arppegioes have been synthesized with the help of a simple compositional subroutine. The last section, where a host of echoes dwindle away, was also realized with MUSIC V, used as a processing and mixing program. Many sounds were proliferated using SYTER, a rea-time digital audio processor designed by Jean-François Allouis at INA-GRM. The composer wishes to thank Daniel Arfib and Pierre Dutilleux, who developed many musical possibilities for SYTER.