Interaction And Spatialization

INTERACTION AND SPATIALIZATION : THREE RECENT MUSICAL WORKS

Jean-Claude Risset CNRS, Laboratoire de Mécanique et d’Acoustique, Marseille
table, to avoid feedback and pick-up of unwanted sounds : however this is not strictly necessary. The processing consists almost only of adding echoes (delayed copies of the original sound) or harmonization (copies of the original sound both delayed andtransposed in pitch). In general four echoes are added. The echoes – transposed or not – are sent into alternate stereo channels, so that they also achieve some kind of spatial widening or ping-pong like bounce. In certain cases, some feedback is introduced : a percentage of the output of the processed sound is sent back to the input of the processing, which enhances or amplifies the processing. Ifthe echoes are not transposed in pitch, feedback causes a longer reverberation. If they are transposed, feedback pursues the transposition upward or downward. Feedback can yield powerful effects, but it should be carefully controlled. The patch is shown on fig. 1. The delays between the echoes– transposed or not – range from a few milliseconds to more than ten seconds. Untransposed echoes delayed bya few milliseconds produce mostly spectral coloration. Around a few dozen of milliseconds, untransposed echoes cause some kind of broadening of the spatial image; long delays can give the impression of a large space – until they are perceived as aurally distinct echoes. If the soloist plays motives, the echoes respond in canon. The celtic harp is normally tuned to a E-flat diatonic scale, buteach string can be tuned individually. Also each string can independently be raised by one semitone using a kind of pin attached at the upper end of the string. The piece Echappées uses a scale in which most steps belong to the tempered scale, except for five of them, which depart from the tempered scale by a quarter-tone. The transposed echoes correspond to one of a few harmonic patterns, selectedin relation to the melodic and harmonic motives to be played by the soloist. The transposition intervals range from one semitone or less to two octaves. Certain transposition intervals used in the piece do not correspond to an integer number of semi-tones : then the resulting tones will depart substantially from the tempered scale.

ABSTRACT This presentation will describe the use of interactionand spatialization in the realization of three recent musical works. In Echappées, the computer responds to the live celtic harp by echoes or harmonizations produced with MaxMSP. Resonant Sound Spaces and Pentacle resort to the tape, either alone for the former or in dialogue with the harpsichord played live for the latter. For these two pieces, real-time synthesis and processing have been used toproduce sound material for the tape, and a 8track spatialization has been elaborated, using the Holophon software designed by Laurent Pottier at GMEM. The presentation will be illustrated by sound examples. 1. INTRODUCTION

This presentation will describe the use of interaction and spatialization in the realization of three recent musical works by the author. 2. LIVE INTERACTION IN ECHAPPEESEchappées is a work for celtic harp and real-time digital processing. It was dedicated to the late Denise Mégevand, who played a unique role in promoting the celtic harp as a significant instrument for contemporary music : she developped novel performance techniques and she incited composers to write pieces for this instrument. Echappées was premiered on february 14, 2004, during theconcert-atelier "Celtik" of the Groupe de Musique Expérimentale de Marseille (GMEM) (this was Denise Mégevand's last public appearance). The celtic harp lends itself very well to a dialogue with an electronic part while maintaining its distinctive identity and its ancient roots. In 1991, the author wrote Lurai, a piece where the celtic harp dialogues with a tape comprising both synthetic sounds and harp...