THE Winthrop House Festival began last Tuesday evening with the music of the Belgian avantgarde composer Henri Pousseur. Assisted by pianist Marcelle Mercenier, Pousseur provided an evening of mixed successes and failures, a program of roughly hewn brilliance which can still stand improvement.

Miroir de Votre Faust for piano solo opened the program. The piece depends to large extent on improvisation in concert by the performer. Mme. Mercenier rose to the occasion, displaying creative as well as interpretive powers by giving life and rhythm to metrically unnoticed sections. Miroir offers the musician other problems and pleasures. The pages, unbound so that the music can be shuffled around before performance, contain many "windows"--rectangular holes that allow one to see through to the next one or two pages. The performer cannot be sure what is coming next or what will return in an entirely new context.

Miroir soars and sparkles on occasion, but fails to sustain a high level of quality throughout. The piece's major fault is that it lacks any logic to carry the listener through. The serial composition is by the composer's own admission, a musical almanac "going from Beethoven to Schoenberg in five minutes." Harmonically it shows a startling resourcefulness, both tonal and non-tonal. Particularly amusing was the recurrence of a particularly slushy theme, either because of the humorous contrast with Pousseur's art, or perhaps due to its explicit banality in the Pousseur context.

Trois Visages de Liege (1961), ending the first half, was played on Ampex and Sony tape decks, McIntosh amplifiers, and six large speaker enclosures along the walls. The first Visage, "L'air et l'eau," was dull, using everyday electronic sounds to no new effects. It sounded distressingly like the background music to either an aspirin commercial or a spaceranger episode. "Voix de la Ville" and "Forges," on the other hand, were fresh, and full of exciting ideas, unusual sounds creating a wide range of mental images: massive steam engines running wild, fiery boilers bursting at the seams; or perhaps the violent battle between Orlando and Mandraicado, hundred-foot giants astride equally powerful and creaky iron stallions.

COMPLETING the program was Jeu de Miroir de Votre Faust for piano and tapes, controlled respectively by Mme. Mercenier and M. Pousseur. Jeu is a reflection upon both Miroir and Votre Faust, Pousseur's newly-completed opera. Created expressly for this concert, Jeu is a reduced version of Miroir with electronic sounds superimposed. A favorite was the conspicuous return of Miroir's syrupy melody followed by a gripping cry of anguish from the loudspeakers. It was good to see this theme receive its just desserts.

Jeu de Miroir de Votre Faust was hurt by the poor technical quality of the tapes. Distortion was evident in places and the entire tape collection seemed hurriedly prepared. M. Peusseur later substantiated this suspicion and stated that he was going to "destroy the tape immediately." For those who were not able to come, tant pis!