PARIS -- Olivier Messiaen, 83, whose devout Catholic faith inspired more than half a century of influential, sometimes perplexing music and helped him become one of France's most respected composers, died April 27 at a hospital here after surgery for an undisclosed ailment.

He earned an international reputation with compositions based on his studies of Oriental music and bird songs and scale formulas of his own invention. He was widely considered to be the most renowned French composer since Maurice Ravel, who died in 1937.

As a professor at the prestigious Paris Conservatory for nearly four decades, he left an indelible mark on some of the 20th century's leading musical figures, including two of his students, Pierre Boulez and Karl Heinz Stockhausen.

Mr. Messiaen, who began composing at the age of 8, was born in Avignon. His father, Pierre Messiaen, was a Shakespearean scholar, and his mother, Cecile Sauvage, a poet. In 1919, the younger Mr. Messiaen entered the Paris Conservatory. He graduated in 1930 with the school's top honors in piano accompaniment, improvisation on the organ, counterpoint and fugue, and musical composition.

He was named organist of the Church of the Trinity in Paris in 1931, where he shocked parishioners with his often violently emotional playing style. From 1936 to 1939, he taught at the Ecole Normale and the Schola Cantorum. In 1939, he became professor at the Paris Conservatory.

In a German prisoner-of-war camp during World War II, he wrote and performed "Quartet for the End of Time."

He held the firm belief that music was closely linked to other disciplines, including philosophy, with its notions of time, duration and folklore. He studied Hindu rhythm, Greek meter and theology. He did pioneering work in the musical notation and classification of birdcalls according to species and habitat.

He traveled widely, tireless in his efforts to record the different bird songs that eventually would become integral parts of his unusual scores.

In 1983, he composed his first opera, "St. Francis of Assisi," a long, complex work praised by many critics. The opera's premiere was directed by Seiji Ozawa, lead conductor of the Boston Symphony. The three-act creation took Messiaen eight years to complete.

Mr. Messiaen once said he "could hear colors." His last composition was an eight-minute work called "Sourire," written last year to mark the bicentennial of Mozart's death.

In 1978, more than 100 concerts of his work were given around the world in three months. His best-known works include "l'Ascension" for orchestra (1935), "La Nativite du Seigneur" (1936), "Le Banquet Celeste" (1936), "Le Corps Glorieux" for organ (1939), "Visions de l'Amen" for two pianos (1943), "Oiseaux Exotiques" (1956) and "Turangalila" (1946-48), a symphony in 10 movements regarded as one of his most elaborate expressions of religious faith.

He was married to the prominent pianist Yvonne Loriod. He married her in 1961 after the death of his first wife, Claire, with whom he had a son, Pascal.