PETER SCHICKELE has been inflicting the music of P.D.Q. Bach on a beleaguered public for ten long years now, even since his first, fateful discovery of the manuscript version of the Sanka Cantata in a Leipzig brothel. P.D.Q., apparently no relation to the well-known J.S. Bach, an earlier baroque composer, plumbed unprecedented depths of mediocrity during his deservedly short lifetime. He has emerged only recently, thanks to Schickele's undoubtedly well-intentioned efforts, from the obscurity that kept him from the public eye for two happy centuries.

Capitalizing on the backlash from Yale's Shockley affair, Schickele managed to obtain permission to present his latest discovery (commissioned by the Harvard Band) at Sanders Theater last weekend. The piece, which he edited--"tastefully," he claims--and retitled Serenoodle for Northerly winds and Percussion, was not originally composed for the concert band. According to Schickele, Bach's original scoring called for "an Awful Lot of wind and Percussion Instruments," a rare combination in the composer's day, but one which the Harvard Band is admirably suited to.

The Serenoodle, true to form, testifies to the perverse taste of its composer, not to mention Schickele. Its sequences are interminable; its modulations not only unexpected, but wholly undesired. Schickele has spent ten years exhuming P.D.Q. Bach compositions with cruel regularity, and with a passion that might best be described as necrophiliac. Surely it is time for music loves everywhere to cry, "Enough."

P.D.Q. BACH'S MUSICAL ineptness was not the sort of thing we can attribute to such simple cause as his dissolute life or his inability to carry a tune. Bach seems to have had little rhythmic sense; indeed, his dance music, as Schickele has aid, suggests that one of his legs was shorter than the other. A lesser problem was his lack of melodic gift. As the third movement of the Serenoodle, entitled "Chorale Prelude," amply demonstrated. P.D.Q. Bach stole tunes from his better freely and without compunction.

His orchestration, on the other hand, was all his own. Not content with the modest range of tone color afforded by conventional instruments, P.D.Q. experimented widely with unusual sound. Few of his innovations made it into the mainstream of Western music, and few who heard the Serenoodle last weekend--with members of the Band's expanded percussion section playing police whistle, duck call popgun cowbell and highly anachronistic electric car horn--will wonder why.

The Band's conductor Thomas G. Everett (who moonlights as president of the international Trombone Association) caught the spirit of P.D.Q. Bach's music, much as millions of P.D.Q.'s contemporaries caught the bubonic plague and various other diseases. After beginning the concert with an accurate and witty performance of Charles Ives's Country Band March. Everett conducted a series of progressively less interesting pieces, as if to lessen the shock of the Serenoodle. And if the Band's playing was occasionally imprecise or out of tune, that was all right. One felt that, somehow, P.D.Q. wouldn't have wanted it any other way.